Ergonomics
ISSN: 0014-0139 (Print) 1366-5847 (Online) Journal homepage: http://www.tandfonline.com/loi/terg20
Grip strength of college and professional football players W.F. STRAUB To cite this article: W.F. STRAUB (1979) Grip strength of college and professional football players, Ergonomics, 22:11, 1185-1194, DOI: 10.1080/00140137908924693 To link to this article: http://dx.doi.org/10.1080/00140137908924693
Published online: 24 Oct 2007.
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Date: 06 November 2015, At: 16:29
ERGONOMICS,
1979, VOL. 22. NO. 11, 1185-1194
Grip strength of college and professional football players By W. F.
STRAUB
Downloaded by [Universite Laval] at 16:29 06 November 2015
Ithaca College, New York, U.S.A. Although strength is basic to human performance in sport. the relationship between grip strength and playing performance has not been clearly established. Therefore, it was the purpose of this study to determine the correlation between grip strength and football playing performance at college and professional levels of competition. The subjects of the investigation were 40 members of an NCAA (Division III) football team and 53 members of an NFL football team. The college players ranged in age from 19 to 22 y. Their mean height was 182-4 em and their average weight was 89'8 kg. The professional players ranged in age from 22 to 37 y. Their mean height was 188'3 em and their average weight was 99'2 kg. They had an average of 5-5 y playing experience in the NFL. Eight of the players had achieved allpro honours. Grip strength was measured with a tensiometer (Model T5, Pacific Scientific Co., Anaheim, California). The criterion measure was the best score of the three trials for dominant and non-preferred hand. Coaches ranked players from best to poorest on playing performance, according to position played. A t-test for independent samples was used to test the significance of mean grip strength scores for offensive and defensive units for the college and professional team. A statistically significant difference (p < 0,001) was found between the mean grip strength scores of the offensive units. The professional offensive players, on the average, were significantly stronger than the college offensive players. Significant differences in grip strength were not found between the defensive units. Rank order correlation coefficients were calculated for positions within offensive and defensive units for both college and professional players. Most of these coefficients were negative, indicating an inverse relationship between grip strength and playing performance. as rated by coaches. Mean grip strength scores for the pro players compared favourably with the scores reported by Ishiko (1974) for Japanese Olympic participants in the 1964 Tokyo Games. Based upon these analyses, it was concluded that grip strength was not correlated significantly with football-playing performance.
1. Introduction At collegiate and professional levels of competition there is a continual search for factors which produce outstanding performances in sport. Although opinions of coaches vary, it is commonly agreed that strength is one of the most important ingredients of playing success, particularly in contact sports like American football. Blocking and tackling require great explosiveness. Thus, the attention given to weight training at high school, college and professional levels of competition attest to the thought that other things being equal, the strongest team usually wins. From an intuitive view, it is easy to accept the premise that strength is vital to success in sport. There is, however, little' hard data' to support this claim. Furthermore, one might ask: 'How much strength is needed?' 'Is the stronger athlete the better athlete?' or, 'Does success depend on how the player uses the strength he/she possesses?' Some all-pro players, for example, never lifted weights and are admittedly weaker than players who play identical positions within the same conference. Quite clearly, there exists a multiplicity of variables underlying success in athletic competition. This fact is particularly true at professional levels where many athletes possess outstanding motor integration, speed, flexibility, cardiovascular and cardiorespiratory endurance, agility, reaction and movement times, and other important fitness and motor performance parameters. After all, a certain amount of strength is of course basic to success in sport, but it is how one utilized strength that may separate 0014·0139/79/22111185 S02.01l
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athletes at professional and world-class levels of competition. Therefore, it was the purpose of this study to compare the grip strength ofcollege and professional football players and determine the relationship between grip strength and football playing performance.
2. Review of literature When we think of professional athletes, particularly American football players, we envisage persons who possess speed, size, balance, agility and endurance but, above all else, great strength. This perspective was not always true, however, since the early physical educators such as Edward Hitchcock, the holder of a chair of Physical Education at Amherst College in 1861, stressed anthropometric measurements for more than 50 years. It is commonly agreed that in 1880 Dudley A. Sargent, Director of the Hemenway Gymnasium at Harvard University, began the strength-testing movement in the United States. Sargent (\904) said that the capacity of the muscles should be given value in judging an individual's fitness. Thus, strength, not size of muscle, became the most important criterion measure of programme effectiveness during the early 1920s. After an early emphasis on anthropometry, the focus changed to function as opposed to the structure of muscles. In brief, performance was more important than appearance. And, in retrospect, it seems that physical educators have never lost sight of this worthy objective. It is true that the current popularity of the aesthetic sports of gymnastics, particularly floor exercise, diving, ice skating, ice dancing, dance and other gross movement activities has increased the interest in body symmetry and proportion, but the attention given to strength has remained constant for more than 75 years. Grip strength, considered to be the best single predictor of total body strength, has been and remains an integral part of contemporary strength assessment programmes. Sargent (I 897) of course included grip strength in his six-item test battery designed to assess physical efficiency. And, much later, Rogers (\ 927) used grip strength as one of the seven components of his strength test that was to become so popular. Since the Sargent (\ 913) and Rogers eras, grip strength studies have appeared at regular frequency in the research and conceptual literature. Blakeman et al. ([934) made a significant contribution when they demonstrated that the hand dynamometer reflected bodily conditions with considerable accuracy. Much later, however, Willgoose (\ 961) reported that grip strength testing should not be considered a substitute for a more thorough measurement of strength.• It is simply a screening device' (Willgoose 1961, p. [30). Willgoose (1947) also examined the relationship between tobacco smoking and grip strength. Using 15 college men as subjects, he found that some individuals were stimulated by smoking and produced higher grip strength scores; others were not aroused and therefore did not score as well as they had before smoking. Willgoose (\947) reported, however, that the recovery times of nonsmokers were better than those of the smokers. Two years later, Kay and Karpovich (1949) confirmed this finding. Of course, all of these studies and the work to follow would not have been possible if Angelo Mosso had not invented the ergograph in 1884. In the 1950s several important contributions were made to the grip strength literature. Slater-Hammel (1950) made the important discovery that exercise of one arm in flexion and extension produced a positive and significant improvement in the
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Grip strength of college and professional football players
I 187
muscular performance of the other. Since Slater-Hammel's report, bilateral effects of muscular activity have become a continual topic ofresearch in physical education, physical therapy and corrective therapy. Bookwalter (1950) developed grip strength achievemen t norms for each hand for boys, girls, and adults. He attempted to control for individual differences by treating grip strength scores for sex, age and weight. In sum, his classification index took these factors into consideration. Perhaps Bookwalter was testing Seaver's (1896) generalization that a large man is not always a strong man and, with equal truth, a strong man is not always the man of high endurance. Turtle et al. (1950) determined the relationship between grip strength and grip strength endurance. They made two important discoveries. First, they found that the greater the maximal grip strength, the less the hand grip time (squeeze time). Second, the person with a stronger grip strength can maintain a higher level of strength for a period of effort than a person of low grip strength. Much later, Bowie and Cumming (1972) found that hand grip time was a possible predictor of motivation to train. However, they did not find a positive correlation between athletic performance and hand grip time (hold time) for boys and girls of 13-17 y. During this same era, Sills and Everett (1953) and Everett and Sills (1952) related grip strength scores to somatotype, stature, and various anthropometric measures. They reported that weight, hand width, height, and mesomorphy were the best predictors of grip strength. In the late 1940s and early 1950s, it was commonly thought that weight training would make athletes muscle-bound and that this condition would result in slower muscular contractions. Zorbas and Karpovich (1951) did much to dispel this belief when they showed that speed of muscular contraction was in fact improved through systematic overload training procedures. Clarke and Henry (1961), Wilkins (1952), and Masley et al. (1953) substantiated Zorbas and Karpovich's finding that strength would not reduce speed of movement. Interested in factors associated with success in Big Ten varsity wrestlers, Kroll (1954) found that average wrestlers were below average in left grip strength. Kroll's work and the work of others suggest that each sport has its own unique pattern of strength requirements. And we might generalize even further to say that each position within a given sport has unique strength demands. In sum, the strength required for the position defensive tackle may be quite different from the strength demands for the position quarterback. Any mention of strength studies without reference to the contributions of H. Harrison Clarke would be incomplete. Clarke (1966, 1971), the editor of the Physical Fitness Research Digest and the author of Muscular Strength and Endurance in Man, conducted the Medford growth study and developed with Munroe the cable tension method for measuring strength (Clark and Munroe 1970). Clarke's (1973, 1974) excellent reviews of muscular strength and the relationship of strength to performance have summarized the growing amount of literature in this area. Diurnal variations in grip strength were reported by Wright (1959). She found a profound fall in grip strength at night and that staying up all night did not alter this pattern. In addition, she reported that immersion of the arm in hot water increased grip strength scores. Wright concluded that diurnal variations may be a manifestation of fundamental body rhythms. Expanding on the early work of Hellebrandt et al. (1962), George (1962), using 12 right-handed and 12 left-handed boys and girls of 5-7 y as subjects, found that left tonic neck reflex in the right-handed subjects has a more facilitative effect than the
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right tonic neck reflex position. In a later study, George and Jackson (1975) investigated the tonic neck posture position on the grip strength scores of institutionalized mental retardates. George et al. (1975) concluded that" grip strength may be a very good reflection of central nervous system (CNS) status in the institutionalized . moderately and mildly retarded" (p. 21). The effects of experimenter expectancy, set and experimenter sex upon grip strength scores was investigated by Rikli (1974). Her subjects were 48 undergraduate males and 48 undergraduate females. Eight graduate males and eight graduate females served as experimenters. Rikli's findings indicated that the male experimenters with the expectancy set obtained results in accordance with their expectations on the grip strength task. Female experimenters, however, obtained results in direct opposition to their expectations. Surprisingly, no cross-sex effect was found. That is, the sex of the experimenter did not influence the grip strength scores of the subjects. The assessment of physical strength is often of interest in epidemiological studies. Willgoose (1961) reported that two practising physicians, Gamboa and Geiss, used grip strength tests in medical practice as aids to the recovery, prognosis and treatment of disease. Their findings showed that recovery from illness was accompanied by a recovery in grip strength. More recently, Lamphiear and Montoye (1976) summarized the findings of their Tecumseh Community Health Study of an entire city in Michigan. Representing 82% of the population, 9226 persons were studied from 1962-1965. The objective of this investigation was to formulate a model for the relationship between strength and body size. Grip strength was one of the variables studied. Most of the explained variations in strength variables was accounted for by five size characteristics: height, weight, biacromial diameter, arm girth and triceps skinfold thickness. Conspicuous by their absence in this review were studies of the grip strength of elite athletes. McCloy (1934), after reviewing several strength studies, concluded that strong arms and shoulder girdles were of even greater importance than back and leg strength for general motor performance. He went on to say that the development of the strength of the upper limbs would improve the performance of any type of athlete. As a kinesiologist, McCloy not only measured the strength of the arms themselves but also the strength of the pectoral, serratus anterior, latissimus dorsi and the deltoideus muscles. The only study that was found which related directly to this one was Ishiko's (1974) investigation of Japanese athletes who trained for the 1964 Olympic Games in Tokyo. The athletes who participated in throwing events, weight lifting, rowing, and judo registered an average grip strength of 637'6 N, whereas the control group recorded only 446'4 N. That is to say, the grip strength of the athletes was approximately 1'5 times that of the control group. Burke (1977) has studied the grip strength of senior male and female physical education major students at a private college in New York State. He reported mean grip strength scores for males (N = 120) and females (N = 115) of 476-4 Nand 255·5 N, respectively. In brief, males were about twice as strong as females.
3. Method 3.1. Subjects. The subjects of this study were 53 members of a National Football League (NFL) team and 40 members of a Division III, National Collegiate Athletic Association (NCAA) football team. The professional players ranged in age from 22 to 37 y with a mean age of 28·2 y. Their average height was 188·3 em and their mean weight was
Grip strength of college and professional football players
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99'2 kg. They had an average of 5' 5 y playing experience in the NFL. Eight of the
players had achieved all-pro honours. The college players ranged in age from 19 to 22 y with a mean age of 20·1 y. Their average height was 182·4 em and their mean weight was 89·8 kg. Several members of this team had participated in the Division 1II, NCAA tournament in 1975 and 1976.
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3.2. Apparatus Grip strength was measured with a Cable Tensiometer (Model Ts, Pacific Scientific Co., Anaheim, California). An orthopaedic attachment (Model T5i66 , Pacific Scientific Co., Anaheim, California) was used to position the tensiometer for grip strength testing. The grip of the orthopaedic attachment was adjustable for persons with different size hands. 3.3. Procedure The subjects were tested according to the procedures specified by Fleishman (1964). Prior to testing and at periodic intervals during the study, the tensiometer was calibrated by hanging known weights from the cable attachment. Each player was tested individually in a room adjacent to the locker room area. He was given three trials with the dominant or preferred hand with a one-minute rest interval interspersed between each trial. The non-preferred hand was then tested. The criterion score for each hand was the best score of the three trials. Only the investigator was present with the subject during test administration. Following each trial, the subject was informed of his score on that trial. Comparative scores of other players were not given. Since data were collected during the pre-season training camp period, subjects were told that their scores would not influence their selection in any way. Particular attention was paid to the correct administration of the test. Subjects were not allowed to bring the tensiometer into contact with their bodies (other than the hand) during grip strength trials. Coaches ranked players from best to poorest at each offensive and defensive position. That is, the offensive line coach ranked players according to their performances at guard, tackle, and centre. The backfield coach ranked the backs, etc. Players were not informed of these rankings.
4. Results Table I shows the mean grip strength scores and their standard deviations for dominant, other, and both hands of offensive and defensive units, as well as, scores by playing position for these groups. As shown, mean grip strength scores for offensive and defensive units within each team did not differ significantly. As expected, the tackles had the highest mean grip strength scores for the professional defensive team. The linebackers, however, were slightly stronger than the tackles for the college defensive squad. Table 2 shows that a significant difference (0,001 level) in mean grip strength scores (both hands) was found between the college and professional offensive players. As expected, the professional players were, on the average, stronger. Surprisingly, however, this finding was not true for the defensive units. There were no statistically significant differences (0,05 level) in mean grip strength scores between the college and professional players.
Total
(2) Offence Centre Guard Tackle Tight end Quarterback Wide receiver Running back
Total
Tackle End Linebacker Safety Cornerback
(I) Defence
Position
21
29·3 40·1 31·0 70·1 00·0 40·9 73·8 40·7
534·7
41·6
57·7 46·9 19·0 43·2 41·0
541·2 525·9 540·8 523-2 601·6 511·7 498·6
555·5
19 2 3 4 2 \ 3 6
577-6 561·8 570·6 505·2 562·4
6 4 2 4 3
N
Dominant S.D. X(N)
Table I.
30·4 43·6 62·4 82·2 00·0 50·0 79·3 49·7
515·1
40·9
532·8 490·5 559·2 495·4 485·6 588·6 507-7 479·0
43-1 50·7 54·5 28·1 28·1
S.D.
551·5 552·5 560·8 489·9 509·5
X(N)
College Other
525-0
515·9 542·6 518·2 504·4 595·2 509·7 488·8
544·2
564·6 557·2 565·7 497-6 536·0
X(N)
Both
28
45·2
I
2 6 7
3 6 3
25
4 4 7 6 4
N
29·9 41·9 46·7 76·2 00·0 45·5 76·5
41·2
50·4 48·8 36·8 35·6 34·5
S.D.
605·3
552·6 588·6 601·6 725·9 603-3 535·6 629·2
589·0
627·8 595·9 591·4 588·6 541·5
38-4
37·9 41·2 64·7 00·0 14·7 69-4 40·7
56-4
61·6 60·6 60·6 71·3 28'1
Dominant X(N) S.D.
Grip strength of collegiate and professional football players
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544·5
526·8 575·5 516·7 667·1 480·7 495·4 549·4
550·5
630·3 571·4 511·5 541·5 497·9
X(N)
Professional Other
53·1
68·1 63-1 51·5 00·0 52·9 58·6 77-2
70-4
70·5 94·2 80-4 64·3 42-4
S.D.
Both
574·8
539·5 582·1 559·2 696·5 542·0 515·0 589·3
570·1
629·1 583·7 551·5 565·1 521·2
X(N)
45·7
53-0 52·2 58·2 00·0 33·8 64·0 59·0
63·4
66·1 77-4 70·5 67·8 35·3
S.D.
"'"
;::
~
V)
:J::
~
~
1191
Grip strength of college and professional football players
Table 2. Means, standard deviations and I-test grip strength values for collegiate and professional football teams.
Professional
College Unit Offence Defence
N
K(N)
S.D.
N
K(N) < < < S.D.
21 19
524·9 544·3
45·2 41·2
28 25
574·8 570·2
45·7 63·5
3·79' 1·54
• Significant at the 0·001 level with df = 47. Table 3.
Rank order correlation of grip strength and college and professional football teams
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College
Wide receiver Defensive end Defensive tackle
Quarterback Linebacker Defensive secondary
Offensive tackle Guard Centre Offensive back
N
Dominant
3 4 5 I 2 4 4 3 2 6
-0,2 -0,3 -0'7 I
-0-4 0·6 -0·5 I
0·03
Hand Other
Professional
Both
N
Dominant
-0,1 -0,25 -0'1
-0'12 -0,3 -0'15
1 -0,6 0 -0·5
I -0'4 0·6 -1 1 -0'26
5 5 4 2 8 10 3 6 3 7
-0'3 -0·6 0-4 -I 0·15 -0·04 0·12 0·43 I -0'21
I
-0'26
Hand Other
Both
0 0 -0,6 -I -0·04 0·27 0·12 0·34
-0·13 -0'6 -0'6 -I -0·01 0·21 0·12 0-41
-I
-I
0·26
-0·43
Table 3 shows the rank order correlation coefficients for dominant, other, and combined hand scores. As shown, most of the coefficients are negative, indicating an inverse relationship between grip strength and playing performance. Evidently, grip strength is not an important variable underlying playing performance. Among the eight players who have achieved all-pro status, they had a mean dominant hand score of 61·9 kg and a mean score of 53·8 kg for the non-preferred hand. These values did not differ significantly from the mean grip strength score for the rest of the professional team members. The player with the strongest grip strength was a defensive tackle. This 24-yearold professional athlete had a score of 725·9 N for the dominant hand and 716·1 N for the non-preferred hand. He was 200·7 em tall and weighed 134·8 kg. The strongest college player was also a defensive tackle. He had a score of 696·5 N for the dominant hand but only 608·2 N for the non-preferred hand. He was 21 y old, . 190·5 cm tall and weighed 99·9 kg. However, he was rated by his coach as poorest performer among the five defensive tackles.
5. Discussion These results are in keeping with the scores reported by Ishiko (1974) for Japanese Olympic athletes who participated in throwing, weight lifting, rowing and judo events in. the 1964 games. Their average grip strength score was 637·6 N compared with 588·6 N for the professional players and 534·6 N for the college athletes. Since there is a decline in grip strength with advancing age, it is understandable why the older professional football players' scores were slightly lower than the scores of the younger Olympic athletes. Several of the professional football players were more than 30 y old. The age factor, however, cannot explain the mean strength difference between the college and Japanese Olympic athletes. This difference was perhaps due to the rigorous selection process for the Olympic team.
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Another factor which influenced grip strength for the college and professional football players was injuries to their hands. Several players scored significantly lower in grip strength in their injured hands. In some instances, the difference in strength was as much as 49-78 N. This problem is reflected in the grip strength scores for the three professional centres (table 3). For the dominant hand, there was a perfect correlation between grip strength and performance. For the non-dominant hand, however, there was a perfect inverse relationship between the two variables. What caused this change was the fact that two of the centres had experienced hand injuries which decreased their grip strength. The fact that the defensive professional tackles achieved the highest mean grip strength scores is not surprising. Since they are the largest men on the team, they are usually the strongest. However, as mentioned previously, there is not a perfect linear relationship between size and strength. And, it is also clearly evident from the results of this study that performance in the NFL and NCAA does not appear to be highly correlated with grip strength. Except for centre, the highest positive correlation between grip strength and performance was 0-43. Thus, grip strength accounted for only 0'19% of the total variance between the two variables. Apparently, other variables must be considered when trying to predict football playing performance. Willgoose (1961) was apparently right when he stated that grip strength is only a rough measure of total body strength. Other strength measures must be taken into consideration. It should be pointed out that both the college and professional teams were successful during the 1976 season. The professional team achieved a 11-3 record; the college team was 6-2 and a draw in 1976 and participated in the NCAA (Division III) Stagg Bowl. It was rated the number two team in the nation in Division III. In conclusion, these data show that grip strength was not highly correlated with football playing performance at college and professional levels of competition. Thanks are extended to Whitney Vantine, Henry Moss and David Sickles for their assistance in data collection. Appreciation is also extended to George Allen, former Head Coach and General Manager of the Washington Redskins, his coaching staff, and players for their cooperation in this study. Appreciation is extended to Philip' Jim' Butterfield, Head Coach of the Ithaca College football team and to the players who participated in this study.
Bien que la force soit un facteur fondamental en sport, la relation entre la force du poignet et les performances sportives n'a pas encore ere nctternent etablie, L'objectif de cette etude a ete de determiner la correlation entre la force du poignet et les performances sportives en football chez des amateurs et des joucurs professionnels. Les sujets etudies provenaient d'une equipe de la NCAA (3e division) qui comprenaient 41 membres et d'une equipe NFL comprenant 60 membres. L'age desjoueurs de l'equipe universitaire etait compris entre 19 et 22 ans ; leur taille moyenne etait de 182'4 em et leur poids moyen de 89'8 kg. L'flge des joueurs professionnels etait compris entre 22 et 37 ans; leur taille moyenne etait de 188'3 em ct leur poids moyen de 99'3 kg. lis avaient un passe commejoueurs de 5'5 annees en moyenne et 8 d'entre cux detenaient Ie diplome de joucurs pro. La force du poignet a ete mesuree a l'aide d'un dynarnometre (modele T5, Pacific Scientific Co, Anaheim, Californie). La valeur critere retenue etait celie qui, sur trois determinations, etait 1a plus elevee, aussi bien sur la main dominante que sur la main non preferee, Les cntraineurs ont donne un rang de c1assement achaque joueur, en fonction du role qu'il tenait sur Ie terrain. Un test t pour echantillons independants a ere utilise pour evalucr les donnees relatives a la dynamornetrie du poignet, chez les attaquants et la defense des deux equipes. Une difference statistiquement significative a ete mise en evidence entre les valeurs dynamometriques moyennes des attaquants. Parmi ceux-ci les profession nels avaient des valeurs plus elevees que les amateurs (p
ISSN: 0014-0139 (Print) 1366-5847 (Online) Journal homepage: http://www.tandfonline.com/loi/terg20
Grip strength of college and professional football players W.F. STRAUB To cite this article: W.F. STRAUB (1979) Grip strength of college and professional football players, Ergonomics, 22:11, 1185-1194, DOI: 10.1080/00140137908924693 To link to this article: http://dx.doi.org/10.1080/00140137908924693
Published online: 24 Oct 2007.
Submit your article to this journal
Article views: 32
View related articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=terg20 Download by: [Universite Laval]
Date: 06 November 2015, At: 16:29
ERGONOMICS,
1979, VOL. 22. NO. 11, 1185-1194
Grip strength of college and professional football players By W. F.
STRAUB
Downloaded by [Universite Laval] at 16:29 06 November 2015
Ithaca College, New York, U.S.A. Although strength is basic to human performance in sport. the relationship between grip strength and playing performance has not been clearly established. Therefore, it was the purpose of this study to determine the correlation between grip strength and football playing performance at college and professional levels of competition. The subjects of the investigation were 40 members of an NCAA (Division III) football team and 53 members of an NFL football team. The college players ranged in age from 19 to 22 y. Their mean height was 182-4 em and their average weight was 89'8 kg. The professional players ranged in age from 22 to 37 y. Their mean height was 188'3 em and their average weight was 99'2 kg. They had an average of 5-5 y playing experience in the NFL. Eight of the players had achieved allpro honours. Grip strength was measured with a tensiometer (Model T5, Pacific Scientific Co., Anaheim, California). The criterion measure was the best score of the three trials for dominant and non-preferred hand. Coaches ranked players from best to poorest on playing performance, according to position played. A t-test for independent samples was used to test the significance of mean grip strength scores for offensive and defensive units for the college and professional team. A statistically significant difference (p < 0,001) was found between the mean grip strength scores of the offensive units. The professional offensive players, on the average, were significantly stronger than the college offensive players. Significant differences in grip strength were not found between the defensive units. Rank order correlation coefficients were calculated for positions within offensive and defensive units for both college and professional players. Most of these coefficients were negative, indicating an inverse relationship between grip strength and playing performance. as rated by coaches. Mean grip strength scores for the pro players compared favourably with the scores reported by Ishiko (1974) for Japanese Olympic participants in the 1964 Tokyo Games. Based upon these analyses, it was concluded that grip strength was not correlated significantly with football-playing performance.
1. Introduction At collegiate and professional levels of competition there is a continual search for factors which produce outstanding performances in sport. Although opinions of coaches vary, it is commonly agreed that strength is one of the most important ingredients of playing success, particularly in contact sports like American football. Blocking and tackling require great explosiveness. Thus, the attention given to weight training at high school, college and professional levels of competition attest to the thought that other things being equal, the strongest team usually wins. From an intuitive view, it is easy to accept the premise that strength is vital to success in sport. There is, however, little' hard data' to support this claim. Furthermore, one might ask: 'How much strength is needed?' 'Is the stronger athlete the better athlete?' or, 'Does success depend on how the player uses the strength he/she possesses?' Some all-pro players, for example, never lifted weights and are admittedly weaker than players who play identical positions within the same conference. Quite clearly, there exists a multiplicity of variables underlying success in athletic competition. This fact is particularly true at professional levels where many athletes possess outstanding motor integration, speed, flexibility, cardiovascular and cardiorespiratory endurance, agility, reaction and movement times, and other important fitness and motor performance parameters. After all, a certain amount of strength is of course basic to success in sport, but it is how one utilized strength that may separate 0014·0139/79/22111185 S02.01l
i~
1979 Taylor & Francis Ltd
1186
W. H. Straub
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athletes at professional and world-class levels of competition. Therefore, it was the purpose of this study to compare the grip strength ofcollege and professional football players and determine the relationship between grip strength and football playing performance.
2. Review of literature When we think of professional athletes, particularly American football players, we envisage persons who possess speed, size, balance, agility and endurance but, above all else, great strength. This perspective was not always true, however, since the early physical educators such as Edward Hitchcock, the holder of a chair of Physical Education at Amherst College in 1861, stressed anthropometric measurements for more than 50 years. It is commonly agreed that in 1880 Dudley A. Sargent, Director of the Hemenway Gymnasium at Harvard University, began the strength-testing movement in the United States. Sargent (\904) said that the capacity of the muscles should be given value in judging an individual's fitness. Thus, strength, not size of muscle, became the most important criterion measure of programme effectiveness during the early 1920s. After an early emphasis on anthropometry, the focus changed to function as opposed to the structure of muscles. In brief, performance was more important than appearance. And, in retrospect, it seems that physical educators have never lost sight of this worthy objective. It is true that the current popularity of the aesthetic sports of gymnastics, particularly floor exercise, diving, ice skating, ice dancing, dance and other gross movement activities has increased the interest in body symmetry and proportion, but the attention given to strength has remained constant for more than 75 years. Grip strength, considered to be the best single predictor of total body strength, has been and remains an integral part of contemporary strength assessment programmes. Sargent (I 897) of course included grip strength in his six-item test battery designed to assess physical efficiency. And, much later, Rogers (\ 927) used grip strength as one of the seven components of his strength test that was to become so popular. Since the Sargent (\ 913) and Rogers eras, grip strength studies have appeared at regular frequency in the research and conceptual literature. Blakeman et al. ([934) made a significant contribution when they demonstrated that the hand dynamometer reflected bodily conditions with considerable accuracy. Much later, however, Willgoose (\ 961) reported that grip strength testing should not be considered a substitute for a more thorough measurement of strength.• It is simply a screening device' (Willgoose 1961, p. [30). Willgoose (1947) also examined the relationship between tobacco smoking and grip strength. Using 15 college men as subjects, he found that some individuals were stimulated by smoking and produced higher grip strength scores; others were not aroused and therefore did not score as well as they had before smoking. Willgoose (\947) reported, however, that the recovery times of nonsmokers were better than those of the smokers. Two years later, Kay and Karpovich (1949) confirmed this finding. Of course, all of these studies and the work to follow would not have been possible if Angelo Mosso had not invented the ergograph in 1884. In the 1950s several important contributions were made to the grip strength literature. Slater-Hammel (1950) made the important discovery that exercise of one arm in flexion and extension produced a positive and significant improvement in the
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Grip strength of college and professional football players
I 187
muscular performance of the other. Since Slater-Hammel's report, bilateral effects of muscular activity have become a continual topic ofresearch in physical education, physical therapy and corrective therapy. Bookwalter (1950) developed grip strength achievemen t norms for each hand for boys, girls, and adults. He attempted to control for individual differences by treating grip strength scores for sex, age and weight. In sum, his classification index took these factors into consideration. Perhaps Bookwalter was testing Seaver's (1896) generalization that a large man is not always a strong man and, with equal truth, a strong man is not always the man of high endurance. Turtle et al. (1950) determined the relationship between grip strength and grip strength endurance. They made two important discoveries. First, they found that the greater the maximal grip strength, the less the hand grip time (squeeze time). Second, the person with a stronger grip strength can maintain a higher level of strength for a period of effort than a person of low grip strength. Much later, Bowie and Cumming (1972) found that hand grip time was a possible predictor of motivation to train. However, they did not find a positive correlation between athletic performance and hand grip time (hold time) for boys and girls of 13-17 y. During this same era, Sills and Everett (1953) and Everett and Sills (1952) related grip strength scores to somatotype, stature, and various anthropometric measures. They reported that weight, hand width, height, and mesomorphy were the best predictors of grip strength. In the late 1940s and early 1950s, it was commonly thought that weight training would make athletes muscle-bound and that this condition would result in slower muscular contractions. Zorbas and Karpovich (1951) did much to dispel this belief when they showed that speed of muscular contraction was in fact improved through systematic overload training procedures. Clarke and Henry (1961), Wilkins (1952), and Masley et al. (1953) substantiated Zorbas and Karpovich's finding that strength would not reduce speed of movement. Interested in factors associated with success in Big Ten varsity wrestlers, Kroll (1954) found that average wrestlers were below average in left grip strength. Kroll's work and the work of others suggest that each sport has its own unique pattern of strength requirements. And we might generalize even further to say that each position within a given sport has unique strength demands. In sum, the strength required for the position defensive tackle may be quite different from the strength demands for the position quarterback. Any mention of strength studies without reference to the contributions of H. Harrison Clarke would be incomplete. Clarke (1966, 1971), the editor of the Physical Fitness Research Digest and the author of Muscular Strength and Endurance in Man, conducted the Medford growth study and developed with Munroe the cable tension method for measuring strength (Clark and Munroe 1970). Clarke's (1973, 1974) excellent reviews of muscular strength and the relationship of strength to performance have summarized the growing amount of literature in this area. Diurnal variations in grip strength were reported by Wright (1959). She found a profound fall in grip strength at night and that staying up all night did not alter this pattern. In addition, she reported that immersion of the arm in hot water increased grip strength scores. Wright concluded that diurnal variations may be a manifestation of fundamental body rhythms. Expanding on the early work of Hellebrandt et al. (1962), George (1962), using 12 right-handed and 12 left-handed boys and girls of 5-7 y as subjects, found that left tonic neck reflex in the right-handed subjects has a more facilitative effect than the
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W. H. Straub
right tonic neck reflex position. In a later study, George and Jackson (1975) investigated the tonic neck posture position on the grip strength scores of institutionalized mental retardates. George et al. (1975) concluded that" grip strength may be a very good reflection of central nervous system (CNS) status in the institutionalized . moderately and mildly retarded" (p. 21). The effects of experimenter expectancy, set and experimenter sex upon grip strength scores was investigated by Rikli (1974). Her subjects were 48 undergraduate males and 48 undergraduate females. Eight graduate males and eight graduate females served as experimenters. Rikli's findings indicated that the male experimenters with the expectancy set obtained results in accordance with their expectations on the grip strength task. Female experimenters, however, obtained results in direct opposition to their expectations. Surprisingly, no cross-sex effect was found. That is, the sex of the experimenter did not influence the grip strength scores of the subjects. The assessment of physical strength is often of interest in epidemiological studies. Willgoose (1961) reported that two practising physicians, Gamboa and Geiss, used grip strength tests in medical practice as aids to the recovery, prognosis and treatment of disease. Their findings showed that recovery from illness was accompanied by a recovery in grip strength. More recently, Lamphiear and Montoye (1976) summarized the findings of their Tecumseh Community Health Study of an entire city in Michigan. Representing 82% of the population, 9226 persons were studied from 1962-1965. The objective of this investigation was to formulate a model for the relationship between strength and body size. Grip strength was one of the variables studied. Most of the explained variations in strength variables was accounted for by five size characteristics: height, weight, biacromial diameter, arm girth and triceps skinfold thickness. Conspicuous by their absence in this review were studies of the grip strength of elite athletes. McCloy (1934), after reviewing several strength studies, concluded that strong arms and shoulder girdles were of even greater importance than back and leg strength for general motor performance. He went on to say that the development of the strength of the upper limbs would improve the performance of any type of athlete. As a kinesiologist, McCloy not only measured the strength of the arms themselves but also the strength of the pectoral, serratus anterior, latissimus dorsi and the deltoideus muscles. The only study that was found which related directly to this one was Ishiko's (1974) investigation of Japanese athletes who trained for the 1964 Olympic Games in Tokyo. The athletes who participated in throwing events, weight lifting, rowing, and judo registered an average grip strength of 637'6 N, whereas the control group recorded only 446'4 N. That is to say, the grip strength of the athletes was approximately 1'5 times that of the control group. Burke (1977) has studied the grip strength of senior male and female physical education major students at a private college in New York State. He reported mean grip strength scores for males (N = 120) and females (N = 115) of 476-4 Nand 255·5 N, respectively. In brief, males were about twice as strong as females.
3. Method 3.1. Subjects. The subjects of this study were 53 members of a National Football League (NFL) team and 40 members of a Division III, National Collegiate Athletic Association (NCAA) football team. The professional players ranged in age from 22 to 37 y with a mean age of 28·2 y. Their average height was 188·3 em and their mean weight was
Grip strength of college and professional football players
1189
99'2 kg. They had an average of 5' 5 y playing experience in the NFL. Eight of the
players had achieved all-pro honours. The college players ranged in age from 19 to 22 y with a mean age of 20·1 y. Their average height was 182·4 em and their mean weight was 89·8 kg. Several members of this team had participated in the Division 1II, NCAA tournament in 1975 and 1976.
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3.2. Apparatus Grip strength was measured with a Cable Tensiometer (Model Ts, Pacific Scientific Co., Anaheim, California). An orthopaedic attachment (Model T5i66 , Pacific Scientific Co., Anaheim, California) was used to position the tensiometer for grip strength testing. The grip of the orthopaedic attachment was adjustable for persons with different size hands. 3.3. Procedure The subjects were tested according to the procedures specified by Fleishman (1964). Prior to testing and at periodic intervals during the study, the tensiometer was calibrated by hanging known weights from the cable attachment. Each player was tested individually in a room adjacent to the locker room area. He was given three trials with the dominant or preferred hand with a one-minute rest interval interspersed between each trial. The non-preferred hand was then tested. The criterion score for each hand was the best score of the three trials. Only the investigator was present with the subject during test administration. Following each trial, the subject was informed of his score on that trial. Comparative scores of other players were not given. Since data were collected during the pre-season training camp period, subjects were told that their scores would not influence their selection in any way. Particular attention was paid to the correct administration of the test. Subjects were not allowed to bring the tensiometer into contact with their bodies (other than the hand) during grip strength trials. Coaches ranked players from best to poorest at each offensive and defensive position. That is, the offensive line coach ranked players according to their performances at guard, tackle, and centre. The backfield coach ranked the backs, etc. Players were not informed of these rankings.
4. Results Table I shows the mean grip strength scores and their standard deviations for dominant, other, and both hands of offensive and defensive units, as well as, scores by playing position for these groups. As shown, mean grip strength scores for offensive and defensive units within each team did not differ significantly. As expected, the tackles had the highest mean grip strength scores for the professional defensive team. The linebackers, however, were slightly stronger than the tackles for the college defensive squad. Table 2 shows that a significant difference (0,001 level) in mean grip strength scores (both hands) was found between the college and professional offensive players. As expected, the professional players were, on the average, stronger. Surprisingly, however, this finding was not true for the defensive units. There were no statistically significant differences (0,05 level) in mean grip strength scores between the college and professional players.
Total
(2) Offence Centre Guard Tackle Tight end Quarterback Wide receiver Running back
Total
Tackle End Linebacker Safety Cornerback
(I) Defence
Position
21
29·3 40·1 31·0 70·1 00·0 40·9 73·8 40·7
534·7
41·6
57·7 46·9 19·0 43·2 41·0
541·2 525·9 540·8 523-2 601·6 511·7 498·6
555·5
19 2 3 4 2 \ 3 6
577-6 561·8 570·6 505·2 562·4
6 4 2 4 3
N
Dominant S.D. X(N)
Table I.
30·4 43·6 62·4 82·2 00·0 50·0 79·3 49·7
515·1
40·9
532·8 490·5 559·2 495·4 485·6 588·6 507-7 479·0
43-1 50·7 54·5 28·1 28·1
S.D.
551·5 552·5 560·8 489·9 509·5
X(N)
College Other
525-0
515·9 542·6 518·2 504·4 595·2 509·7 488·8
544·2
564·6 557·2 565·7 497-6 536·0
X(N)
Both
28
45·2
I
2 6 7
3 6 3
25
4 4 7 6 4
N
29·9 41·9 46·7 76·2 00·0 45·5 76·5
41·2
50·4 48·8 36·8 35·6 34·5
S.D.
605·3
552·6 588·6 601·6 725·9 603-3 535·6 629·2
589·0
627·8 595·9 591·4 588·6 541·5
38-4
37·9 41·2 64·7 00·0 14·7 69-4 40·7
56-4
61·6 60·6 60·6 71·3 28'1
Dominant X(N) S.D.
Grip strength of collegiate and professional football players
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544·5
526·8 575·5 516·7 667·1 480·7 495·4 549·4
550·5
630·3 571·4 511·5 541·5 497·9
X(N)
Professional Other
53·1
68·1 63-1 51·5 00·0 52·9 58·6 77-2
70-4
70·5 94·2 80-4 64·3 42-4
S.D.
Both
574·8
539·5 582·1 559·2 696·5 542·0 515·0 589·3
570·1
629·1 583·7 551·5 565·1 521·2
X(N)
45·7
53-0 52·2 58·2 00·0 33·8 64·0 59·0
63·4
66·1 77-4 70·5 67·8 35·3
S.D.
"'"
;::
~
V)
:J::
~
~
1191
Grip strength of college and professional football players
Table 2. Means, standard deviations and I-test grip strength values for collegiate and professional football teams.
Professional
College Unit Offence Defence
N
K(N)
S.D.
N
K(N) < < < S.D.
21 19
524·9 544·3
45·2 41·2
28 25
574·8 570·2
45·7 63·5
3·79' 1·54
• Significant at the 0·001 level with df = 47. Table 3.
Rank order correlation of grip strength and college and professional football teams
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College
Wide receiver Defensive end Defensive tackle
Quarterback Linebacker Defensive secondary
Offensive tackle Guard Centre Offensive back
N
Dominant
3 4 5 I 2 4 4 3 2 6
-0,2 -0,3 -0'7 I
-0-4 0·6 -0·5 I
0·03
Hand Other
Professional
Both
N
Dominant
-0,1 -0,25 -0'1
-0'12 -0,3 -0'15
1 -0,6 0 -0·5
I -0'4 0·6 -1 1 -0'26
5 5 4 2 8 10 3 6 3 7
-0'3 -0·6 0-4 -I 0·15 -0·04 0·12 0·43 I -0'21
I
-0'26
Hand Other
Both
0 0 -0,6 -I -0·04 0·27 0·12 0·34
-0·13 -0'6 -0'6 -I -0·01 0·21 0·12 0-41
-I
-I
0·26
-0·43
Table 3 shows the rank order correlation coefficients for dominant, other, and combined hand scores. As shown, most of the coefficients are negative, indicating an inverse relationship between grip strength and playing performance. Evidently, grip strength is not an important variable underlying playing performance. Among the eight players who have achieved all-pro status, they had a mean dominant hand score of 61·9 kg and a mean score of 53·8 kg for the non-preferred hand. These values did not differ significantly from the mean grip strength score for the rest of the professional team members. The player with the strongest grip strength was a defensive tackle. This 24-yearold professional athlete had a score of 725·9 N for the dominant hand and 716·1 N for the non-preferred hand. He was 200·7 em tall and weighed 134·8 kg. The strongest college player was also a defensive tackle. He had a score of 696·5 N for the dominant hand but only 608·2 N for the non-preferred hand. He was 21 y old, . 190·5 cm tall and weighed 99·9 kg. However, he was rated by his coach as poorest performer among the five defensive tackles.
5. Discussion These results are in keeping with the scores reported by Ishiko (1974) for Japanese Olympic athletes who participated in throwing, weight lifting, rowing and judo events in. the 1964 games. Their average grip strength score was 637·6 N compared with 588·6 N for the professional players and 534·6 N for the college athletes. Since there is a decline in grip strength with advancing age, it is understandable why the older professional football players' scores were slightly lower than the scores of the younger Olympic athletes. Several of the professional football players were more than 30 y old. The age factor, however, cannot explain the mean strength difference between the college and Japanese Olympic athletes. This difference was perhaps due to the rigorous selection process for the Olympic team.
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W. H. Straub
Another factor which influenced grip strength for the college and professional football players was injuries to their hands. Several players scored significantly lower in grip strength in their injured hands. In some instances, the difference in strength was as much as 49-78 N. This problem is reflected in the grip strength scores for the three professional centres (table 3). For the dominant hand, there was a perfect correlation between grip strength and performance. For the non-dominant hand, however, there was a perfect inverse relationship between the two variables. What caused this change was the fact that two of the centres had experienced hand injuries which decreased their grip strength. The fact that the defensive professional tackles achieved the highest mean grip strength scores is not surprising. Since they are the largest men on the team, they are usually the strongest. However, as mentioned previously, there is not a perfect linear relationship between size and strength. And, it is also clearly evident from the results of this study that performance in the NFL and NCAA does not appear to be highly correlated with grip strength. Except for centre, the highest positive correlation between grip strength and performance was 0-43. Thus, grip strength accounted for only 0'19% of the total variance between the two variables. Apparently, other variables must be considered when trying to predict football playing performance. Willgoose (1961) was apparently right when he stated that grip strength is only a rough measure of total body strength. Other strength measures must be taken into consideration. It should be pointed out that both the college and professional teams were successful during the 1976 season. The professional team achieved a 11-3 record; the college team was 6-2 and a draw in 1976 and participated in the NCAA (Division III) Stagg Bowl. It was rated the number two team in the nation in Division III. In conclusion, these data show that grip strength was not highly correlated with football playing performance at college and professional levels of competition. Thanks are extended to Whitney Vantine, Henry Moss and David Sickles for their assistance in data collection. Appreciation is also extended to George Allen, former Head Coach and General Manager of the Washington Redskins, his coaching staff, and players for their cooperation in this study. Appreciation is extended to Philip' Jim' Butterfield, Head Coach of the Ithaca College football team and to the players who participated in this study.
Bien que la force soit un facteur fondamental en sport, la relation entre la force du poignet et les performances sportives n'a pas encore ere nctternent etablie, L'objectif de cette etude a ete de determiner la correlation entre la force du poignet et les performances sportives en football chez des amateurs et des joucurs professionnels. Les sujets etudies provenaient d'une equipe de la NCAA (3e division) qui comprenaient 41 membres et d'une equipe NFL comprenant 60 membres. L'age desjoueurs de l'equipe universitaire etait compris entre 19 et 22 ans ; leur taille moyenne etait de 182'4 em et leur poids moyen de 89'8 kg. L'flge des joueurs professionnels etait compris entre 22 et 37 ans; leur taille moyenne etait de 188'3 em ct leur poids moyen de 99'3 kg. lis avaient un passe commejoueurs de 5'5 annees en moyenne et 8 d'entre cux detenaient Ie diplome de joucurs pro. La force du poignet a ete mesuree a l'aide d'un dynarnometre (modele T5, Pacific Scientific Co, Anaheim, Californie). La valeur critere retenue etait celie qui, sur trois determinations, etait 1a plus elevee, aussi bien sur la main dominante que sur la main non preferee, Les cntraineurs ont donne un rang de c1assement achaque joueur, en fonction du role qu'il tenait sur Ie terrain. Un test t pour echantillons independants a ere utilise pour evalucr les donnees relatives a la dynamornetrie du poignet, chez les attaquants et la defense des deux equipes. Une difference statistiquement significative a ete mise en evidence entre les valeurs dynamometriques moyennes des attaquants. Parmi ceux-ci les profession nels avaient des valeurs plus elevees que les amateurs (p
