dctu
Physiol Scund 1990, 141, 149-156
ADONIS 000 1677291000255
Responses t o eccentric and concentric resistance training in females and males E. B. C O 1 , L I A N D E R and P. A. T E S C H Environmental Physiology Laboratory, Department of Physiology, Karolinska Institutet, Stockholm, Sweden E. B. & TESCH, P. A. 1991. Responses to eccentric and concentric resistance training in females and males. Actu Ph,ysiol Scund 141, 149-156. Received 21 August 1990, accepted 3 October 1990. ISSN 0001-6772. Environmental Physiology Laboratory, Department of Physiology, Karolinska Institute, Sweden. C oL L I ANm R,
The adaptive responses to 12 weeks of accommodated resistance training were compared in females ( n = 11) and males ( n = 11). They performed four to five sets of six maximum bilateral coupled concentric and eccentric quadriceps muscle actions at 1.05 rad s-' three times per week. Uni- and bilateral concentric and eccentric peak torque at different angular velocities (0.52, 1.57 and 2.62 rad s ~ ' ) , three repetition maximum half-squat and vertical jump height were measured before and after training. Both groups displayed marked increases (P< 0.05) in concentric and eccentric peak torque at all angular velocities. The relative increases (P< 0.05) in unilateral concentric (26 us. 26%) and eccentric (28 us. 36%) peak torque across speeds were similar in females and males. The corresponding increases (P< 0.05) in bilateral concentric and eccentric peak torque across speeds were 20 us. 28% and 24 us. 39% respectively. The three repetition maximum half-squat (20 us. 25 7;)and vertical jump height (10 us. 8%) increased (P< 0.05) equally in females and males. These results suggest that the overall increases in concentric and eccentric peak torque and functional strength, in response to short-term accommodated resistance training, occur at a rate that is independent of sex. The torque-velocity relationship, however, appears to change in males suggesting a relatively greater enhancement of maximum voluntary force in the slow-speed, high-force region. Key words : Accommodated resistance, muscular strength, quadriceps peak torque
From previous studies it has been concluded that females and males benefit from short-term resistance training programmes by similar relative increases in lower limb muscle strength (Wilmore 1974, O'Shea & Wegner 1981, Cureton et al. 1988, Weiss et al. 1988). Although these training regimens comprised coupled concentric and eccentric muscle actions, changes in strength were assessed by means of the maximum voluntary contraction (MVC) or the one repetition maximum (1 R M ) techniques. Neither study measured and compared concentric and eccentric strength at various angular velocities. Correspondence : E. B. Colliander, Environmental Physiology Laboratory, Department of Physiology, Box 60 400, Karolinska Institutet, S-104 01 Stockholm, Sweden.
Eccentric peak torque normalized for body weight, is similar but concentric peak torque is lower in females than in males (Colliander & Tesch 1989). Similarly, it has been shown that the ability to utilize elastic energy during jumping activities is greater in females than in males (Komi & Bosco 1978). T h e underlying mechanism(s) for this apparent sex difference is unknown. There are data available, however, to suggest that force generated during a maximum voluntary eccentric muscle action is markedly impaired (Gravel et al. 1987, Triolo et ul. 1987). I f this phenomenon is more pronounced in males it may, at least in part, explain the difference in eccentric relative to concentric strength between females and males. T h e initial increases in muscle strength observed in response to resistance exercise have mainly been attributed
149 6
ACT 141
150
E . B . Colliander and P. A . Tesch
to neural mechanisms (Moritani & deVries 1979)
such as enhanced neural drive ( K o m i 1986) or reduced antagonistic activity (Caiozzo et al. 1981, Hakkinen & Komi 1983). We therefore speculated that males would show greater increase in eccentric strength in response to a short-term resistance training programme which produced substantial increases in strength despite no apparent muscle hypertrophy (Colliander & Tesch 1990). This study therefore compared the effects of a short-term accommodated resistance training programme comprising coupled concentric and eccentric maximum voluntary quadriceps muscle actions in females and males. I t was the purpose to examine changes in performance of concentric and eccentric muscle actions a t various angular velocities a n d functional strength dependent activities.
M A T E R I A L S AND M E T H O D S Subjects
Females ( n = 14) and males ( n = 14) with asymptomatic knee function volunteered for this study. Although physically active they had never participated in regular strength training programmes. T h e habitual activity level of all subjects was maintained during the experimental period. The protocol utilized was approved by the Karolinska Institute Ethics Committee. Subjects gave informed consent and could withdraw their participation at any time during the study. Three females and three males failed to complete the programme due to muscle strains or time constraints. Each group therefore consisted of 11 subjects (Table 1). Seven age-matched males, who did not train, served as controls. They showed no changes in the performance variables measured (see below) over the experimental period (for details see Colliander & Tesch 1990).
Training T h e training programme employed has been described in detail elsewhere (Colliander & Tesch 1990). Briefly, subjects trained three times a week for 12 weeks under supervision. Four to five sets of six maximum bilateral coupled concentric and eccentric muscle actions at a constant angular velocity of 1.05 rad s-' were performed. Each set was followed by a 1.5-2 min rest. From week 4 two male subjects performed unilateral training because of unexpected strength gains resulting in torque outputs interfering with the control of constant angular velocity. Recordings of bilateral were therefore eccentric muscle actions at 0.52 rad SKI
not performed. In addition, four sets of 1&12 repetition maximum (RM) hamstring leg-curls were performed using variable resistance.
Testing Subjects were instructed and acquainted with the training and testing devices and procedures on two occasions prior to the first test. Examinations were made before and after 4, 8 and 12 weeks. The dynamometer (Tesch et ul. 1990) and the procedures (Colliander & Tesch 1989, 1990) used in this study have been described elsewhere. Briefly, the muscle action modes performed were in order: unilateral concentric (UNI(:oN),bilateral concentric (BILl,l)x), unilateral eccentric (UNI Ec(:) and bilateral eccentric (BILM.,r) at constant angular velocities corresponding to 0.52, 1.57 and 2.62 rad S K I .Torque curves were recorded on a strip-chart recorder (Gould 2400, Gould Inc., Cleveland, OH, USA). Peak torque and body weight corrected peak torque were subsequently calculated. Lateral and frontal skinfolds and circumferences of the thigh were measured at one- and two-thirds of the distance between spina iliaca anterior superior and the lateral knee joint line of both limbs. Thereafter, a 10 min warm-up period was followed by measurement of vertical jump height (VJH). Vertical jumps were performed from a deep squatting position with no counter-movement allowed and VJH was defined as the highest value among five trials. Maximum quadriceps muscle actions were then performed and peak torque recorded (see above) and 3 RM half-squat using a barbell was assessed.
Statistics Mean and standard deviation (SD) were calculated and potential intra- and inter-group variations were tested for using analysis of variance (ANOVA). The following model was applied: xLjki= /L +a, B,,L, y r 6, +interaction terms where p = grand mean of test subjects; at=fixed effect of = random group; i = 1 for females, 2 for males, Bj(LJ effect ofsubject within group;; = number ofsubjects; yA.= fixed effect of test; k = 1 for Test 1, 2 for Test 2, 3 for Test 3 and 4 for Test 4, 6, = angular velocity within a muscle-action mode; I = 1 for 0.52 rad s-', 2 for 1.57 rad s-' and 3 for 2.62 rad s-'. Test of simple main effects (Kirk 1981) was used when ANOVA demonstrated statistically significant interaction terms. The level of significance was set at P < 0.05.
+
+ +
RESULTS L i m b skinfold decreased with training in females a n d limb circumference increased in males only (Table 1).
151
Resistance training in jirnales and males Table 1. Physical characteristics of females ( n = 11) and males (n = 11). Values are mean 5 SD. group difference. Females
Age (yrs) Height (cm) Weight (km) Limb skinfold (mm) Limb circumference (cm)
*;
= intra-
Males
Pre
Post
Pre
Post
27+4 16556 57.0+ 6.0 20.9i7.6 52.1 k 3.7
-
26k5 180+3 76.4f6.8 12.2t4.4 54.3k3.7
-
56.4 k 6.8 17.7k5.6' 52.1 k 3.6
-
76.0f6.4 11.2f3.8 54.7+3.9+
Table 2. Unilateral quadriceps peak torque (Nm kg--') and eccentric to concentric ratio in females ( n = 11) = inter-group difference in and males ( n = 11). Values are meanf SD. # = inter-group difference; absolute peak torque increase.
+
Concentric Angular velocity rad .s-'
0.52 1.57 2.62
Females
Males
_ _ _ _ _ _ _ _ _ _ _ _ _~-
- _ _ - - - -- _ _
Pre
Post
Pre
Post
2.51 k0.29 1.99+ 0.18 1.64k0.11
3.17k0.43 2.55 f 0.41 2.04k0.36
2.80f0.32# 2.51 +0.27# 2.11+0.20#
3.80_+0.45# 3.08f0.40# 2.49+0.32#
4.48k0.86 4.41 50.83 4.3050.81
3.46k0.47 3.39 5 0.44 3.18 & 0.56
5.01 k0.82 4.43 + a 7 3 4.10_+0.72
+
Eccentric
0.52 1.57 2.62
3.35+0.54 3.51 f0.59 3.49 k0.57
Eccentric/concentric ratio Females
0.52 1.57 2.62
Males
Pre
Post
Pre
Post
1.34f0.20 1.76f0.23 2.13 k0.34
1.41k0.14 1.73k0.19 2.12t0.28
1.24+ 0.18 1.36k0.19 1.52+0.31#
1.31k0.11 1.44k 0.17 1.65+0.23#
Concentric peak torque, relative to body weight, was greater in males than in females before and after training. Eccentric peak torque was not different between groups (Table 2 & 3). Concentric and eccentric peak torque, regardless of angular velocity, increased with
training in both groups (Table 2 & 3). Absolute increases in UNI,.,, (0.52 rad s-'; Table 2 ) and BIL,,, (all angular velocities; Table 3) were greater in males than in females. The relative increases in peak torque across speeds and muscle action modes were 25(% in females and 6-2
E. B . Colliander and P. A . Tesch
152
T a b l e 3. Bilateral quadriceps peak torque (Nm kg-l) in females (n = 11) and males (n = 11). Values are m e a n i S D . # = inter-group difference; -- inter-group difference in absolute peak torque increase.
+
Concentric Angular velocity
Females
rad.s
Pre
Post
Pre
Post
0.52 1.57 2.62
4.77 k 0.74 4.05f0.50 3.30k0.28
5.96 f0.93 4.80k0.72 3.83k0.56
5.32 k 0.86 4+ 4.66+0.57# 3.9440.41#
7.30 k 0.90 # 5.80f0.71 # 4.74f0.65#
0.52 1.57 2.62
6.2611.38 6.82k1.32 6.50k 1.06
-
650-t 1.32 6.264 1.09 5 . 9 2 4 1.12
-
'
Males
8.18k1.61 8.19f 1.69
+ + +
8.57k 1.58 8.07 1.25
T a b l e 4. Relative increase (%) of uni- and bilateral concentric and eccentric quadriceps peak torque for females (n = 11) and males (n = 11). Values are mean$SD. ~
~
~
~
~
_
_
_
Unilateral Angular velocity
Concentric
Eccentric
rad.s-'
Females
Males
Females
Males
0.52 1.57 2.62
27f 14 2 8 1 16 24k21
37+17 23111 18k8
35k23 27+22 24f17
46 f 23 31+20 31 $28
Bilateral Concentric
0 52 1.57 2.62
Eccentric
Females
Males
Females
Males
2 6 k 11 19f 17 16k 12
39119 26f17 21k15
38k16 21f19 26115
-
32% in males (P> 0.05; Table 4. T h e overall increases in peak torque were greater at 0.52 rad s-l than at 2.62 rad s-'. UNI,,, The absolute increases in (0.52 rad s-'; Fig. 1) and BIL,.,, (all angular velocities), over the four testing sessions, were greater in males than in females. Increases in
39 & 34 39 f27
UNIkccc(Fig. 2) and BILE(,,.were not different between groups. Unilateral concentric peak torque decreased with increasing angular velocity in both groups before training (Fig. 3). This decrease was greater in females than in males before, but not after, training. Independent of sex unilateral
_
Resistance training in females and males
153
E
z
-aJ
I
3
-
F 0
4-
Y
P 200 a
-
L I
0
4
I
I
8
12
weeks Fig. 1. Unilateral concentric quadriceps peak torque (Nm kg-') at 0.52 (0, ),. 1.57 (A, A)and 2.62 (0, W ) rad's for females (open symbols) and males (filled symbols). Values are mean. For differences between mean values and slope of curves see Results.
li
3 a
200
d 0
a
4
12
weeks eccentric peak torque did not change with increasing angular velocity (Fig. 3). In a group comparison, however, males showed greater decrease with increasing angular velocity than females after, but not before, training. Unilateral eccentric/concentric peak torque ratio increased more in females than in males with increasing angular velocity (Table 2). The increase in 3 RM half-squat was similar in females (20%) and males (25%). The corresponding increases in VJH were 10 and 8% respectively (Table 5 ) . DISCUSSION In this study the responses to short-term resistance training were compared in females and males. There were similar relative, overall
Fig. 2. Unilateral eccentric quadriceps peak torque (Nm kg-') at 0.52 (0, ,). 1.57 (A, A)and 2.62 (0, ). rad.s-' for females (open symbols) and males (filled symbols). Values are mean. For differences between mean values and slope of curves see Results.
increases in concentric and eccentric quadriceps peak torque and functional strength, suggesting that the rate of increases in strength dependent performances are not markedly different between sexes. Although this study did not provide conclusive evidences to suggest that increases in concentric or eccentric strength were greater in males than in females, only the former showed a change in the torque-velocity relationship. This was provoked by a greater relative increase in the slow-speed and high-force region.
154
E. B. Colliunder und P. A . Tesch Peak torque INm kg-')
T
ECCENTRIC
CONCENTRIC
t /
I
I
2.62
1.57
I
I
1.57
2.62
I
I
0.52 0.52 Angular velocity (rod
5")
Fig. 3. Unilateral eccentric (left panel) and concentric (right panel) quadriceps peak torque (Nm kg I ) in females (open symbols) and males (filled symbols) before (0, 0 )and after (m, 0) training. Values are mean. For differences between mean values and slope of curves see Results. Table 5. 3 RM half-squat and vertical jump height (VJH) in females (n = 11) and males (n = 11). Values are mean SD. " = intra-group difference.
Females Pre -
3 RM half-squat (kg) VJH (cm)
84+ 14 35.9k5.5
Males Post
_ _
Pre
Post
116+13 45.4k3.9
145+15* 49.0k3.5"
---__
102k 16* 39.3k5.3"
Weekly increases in unilateral concentric and eccentric quadriceps peak torque, across speeds, averaged 2.2 and 2.4% in females and 2.2 and 3.07; in males. T h e corresponding increases for bilateral muscle actions were 1.7 and 2.0% in females and 2.4 and 3.2'% in males. These increases are of similar magnitude to those reported for dynamic (i.e. 1 RM) or isometric lower limb muscle strength in females or males performing resistance training with free weights for 8-16 weeks (Wilmore 1974, Cureton et al. 1988, Weiss et al. 1988). T h e relative gains in concentric and eccentric strength were also comparable to those observed subsequent to concentric, eccentric or coupled concentric and eccentric resistance training in males (Komi & Buskirk 1972, Hakkinen & Komi 1981). Such comparisons should however, be regarded with
caution because the improvements are influenced by the initial state of training and the extent to which the trainees are familiarized to carry out the specific exercises and the test procedure. I n concert with previous reports examining the 1 RM (Wilmore 1974, Cureton et al. 1988) absolute, not relative, overall increases in concentric peak torque across speeds, were greater in males than in females. In contrast, the increase in eccentric peak torque, albeit numerically markedly greater in males, did not differ between females and males. This lack of group difference may simply be explained by the larger variability for eccentric compared to concentric peak torque measurements shown here and noticed elsewhere (Komi & Buskirk 1972, Highgenboten et al. 1988, Colliander & Tesch 1989, Tesch et al. 1990). T h e rate of increase in eccentric peak torque,
Resistance training in -females and males especially at the slowest speed examined, plateaued in females but progressed in males. This suggests that the latter may show a greater increase providing the length of the programme is extended. The enhanced strength demonstrated in response to the present resistance training regimen most likely reflects mainly neural adaptations, because increases in muscle fibre size in the male group were small and non-significant, as already reported (Colliander & Tesch 1990). Similarly, the finding of a small increase in limb girth observed in males and a decreased limb skinfold with no change in circumference in females further imply limited increases in muscle crosssectional area and that the hypertrophic response was similar in females and males. Peak torque during concentric muscle actions decreased with increasing angular velocity (Thorstensson et al. 1976, Perrine & Edgerton 1978). Eccentric peak torque, in contrast, did not vary as a function of angular velocity. Similar results for the quadriceps muscle have previously been reported in males (Westing et al. 1988, Dudley et al. 1989) and females (Westing & Seger 1989) performing unilateral muscle actions. There were, however, evidences of differences in the torque-velocity relationship between males and females. Thus, concentric peak torque showed a greater slope of decrease as a function of increased angular velocity in females before but not after training. This change appeared to be produced by the greater increase in peak torque at low angular velocities in males. Because eccentric but not concentric peak torque relative to body weight, was similar in the two groups the increase in the eccentric to concentric peak torque ratio as a function of increased angular velocity, was greater in females than in males. I t has been suggested that the muscle force generated during the performance of slowspeed, maximum voluntary concentric (Perrine & Edgerton 1978) or eccentric (Gravel et al. 1987, Triolo et ul. 1987) muscle actions is impaired probably through neural inhibitive mechanisms. T h e present findings do suggest that the largest changes in response to training occurred in this part of the torque-velocity curve. I n conclusion, short-term accommodated resistance training comprising maximum concentric and eccentric muscle actions produced marked increases in concentric and eccentric
155
muscle strength in males and females. Although the increases in maximum strength across speeds of concentric and eccentric muscle actions and functional strength were of similar magnitude the torque-velocity relationship appeared to be influenced differently depending on sex. This study was supported by grants from the Royal Swedish Air Force and the Karolinska Institute Research Funds.
REFERENCES CAIOZZO, V.J., PERRINE, J.J. & EDGERTON V.R. 1981. Training-induced alterations of the in zivo forcevelocity relationship of human muscle. 3 Appl Physiol 51, 75&754. COLLIANDER, E.B. & TESCH, P.A. 1989. Bilateral eccentric and concentric torque of quadriceps and hamstring muscles in females and males. Eur 3 Appl Physiol 59, 227-232. COLLIANDER, E.B. & TESCH, P.A. 1990. Effects of eccentric and concentric muscle actions in resistance training. Acta Physiol Scand 140, 31-39. CURETON, K.J., COLLINS,M.A., HILL, D.W. & MCELHANNON, JR. F.M. 1988. Muscle hypertrophy in men and women. Med Sct Sports Exerc 20, 338-344. DUDLEY, G.A., DUVOISIN, M.R., CONVERTINO, V.A. & RUCHANAN, P. 1989. Alterations of the in vivo torque-velocity relationship of human skeletal muscle following 30 days exposure to simulated microgravity. Aviat Space Enriron Med 60, 659-663. GRAVEL, D., B~LANGER, A.Y. & RICHARDS, C.L. 1987. Study of human muscle contraction using electrically evoked twitch responses during passive shortening and lengthening movements. EurJ Appl Ph,ysiol 56, 623-627. HIGHGENBOTEN, C.L., JACKSON, A.W. & MESKE,N.B. 1988. Concentric and eccentric torque comparisons for knee extension and flexion in young adult males and females using the Kinetic Communicator. A m 3 Sports Med 16, 23+237. HAKKINEN, K . & KOMI,P.V. 1981. Effects of different combined concentric and eccentric muscle work regimens on maximal strength development. 3Hum Move Stud 7, 33-44. HAKKINEN, K . & KOMI,P.V. 1983. Electromyographic changes during strength training and detraining. Med Sci Sports Exerc 15, 455-460. KIRK,R.E. 1981. Experimental Design: Procedures f u r the behacioral sciences, pp. 263-266. Brooks/Cole Publish Comp. Belmont, CA. KOMI,P.V. 1986. How important is neural drive for strength and power development in human skeletal muscle? I n : Biochemistry of Exercise VI. Saltin B (ed), pp 515-529.
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KOMI,P.V. & BUSKIRK, E.R. 1972.Effect of eccentric and concentric muscle conditioning on tension and electrical activity of human muscle. Ergonomics 15, 4 17434. KOMI,P.V. & Bosco, C. 1978.Utilization of stored elastic energy in leg extensor muscles by men and women. Med Sci Sports 10, 261-265. MORITANI, T. & DEVRIES, H.A. 1979.Neural factors versus hypertrophy in the time course of muscle strength gain. Am 3 Phys Med 58, 115-130. O’SHEA,J.P. & WEGNER,J. 1981. Power weight training and the female athlete. Phys Sportsmed 9, 109-1 20. PERRINE, J.J. & EDGERTON, V.R. 1978. Muscle-force velocity and power-velocity relationships under isokinetic loading. Med Sci S p o r t s 10, 159-166. TESCH, P.A., LINDBORG, B.P.O. & COLLIANDER, E.B. 1990. Evaluation of a dynamometer measuring torque of uni- and bilateral concentric and eccentric muscle action. Clin Physiol 10, 1-9.
THORSTENSSON, A,, GRIMBY, G. & KARLSSON, J. 1976. Force-velocity relations and fiber composition in
3 A p p l Ph,yszol 40, 12-16. TRIOLO, R., ROBINSON, D., GARDNER, E. & BETZ,R. 1987.T h e eccentric strength of electrically stimulated paralyzed muscle. IEEE 7rans Biomed Eng 9, 651-652. WEISS,L.W., CLARK,F.C. & HOWARD, D.G. 1988. human knee extensor muscles.
Effects of heavy-resistance triceps surae muscle training on strength and muscularity of men and women. Phys They 68, 208-213. WESTING, S.H., SEGER, J.Y., KARLSON, E. EKBLOM, B. 1988. Eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man. Eur 3 A p p l Ph,ysiol 58, lO(t104. WESTING, S.H. & SEGER,J.Y. 1989. Eccentric and concentric torque-velocity characteristics, torque output comparisons, and gravity effect torque corrections for the quadriceps and hamstring muscles in females. Znt J Sports Med 10, 175-180. WILMORE, J.H. 1974. Alterations in strength, body composition and anthropometric measurements consequent to a 10-week weight training program. Med Sci Sports 6, 133-138.
Physiol Scund 1990, 141, 149-156
ADONIS 000 1677291000255
Responses t o eccentric and concentric resistance training in females and males E. B. C O 1 , L I A N D E R and P. A. T E S C H Environmental Physiology Laboratory, Department of Physiology, Karolinska Institutet, Stockholm, Sweden E. B. & TESCH, P. A. 1991. Responses to eccentric and concentric resistance training in females and males. Actu Ph,ysiol Scund 141, 149-156. Received 21 August 1990, accepted 3 October 1990. ISSN 0001-6772. Environmental Physiology Laboratory, Department of Physiology, Karolinska Institute, Sweden. C oL L I ANm R,
The adaptive responses to 12 weeks of accommodated resistance training were compared in females ( n = 11) and males ( n = 11). They performed four to five sets of six maximum bilateral coupled concentric and eccentric quadriceps muscle actions at 1.05 rad s-' three times per week. Uni- and bilateral concentric and eccentric peak torque at different angular velocities (0.52, 1.57 and 2.62 rad s ~ ' ) , three repetition maximum half-squat and vertical jump height were measured before and after training. Both groups displayed marked increases (P< 0.05) in concentric and eccentric peak torque at all angular velocities. The relative increases (P< 0.05) in unilateral concentric (26 us. 26%) and eccentric (28 us. 36%) peak torque across speeds were similar in females and males. The corresponding increases (P< 0.05) in bilateral concentric and eccentric peak torque across speeds were 20 us. 28% and 24 us. 39% respectively. The three repetition maximum half-squat (20 us. 25 7;)and vertical jump height (10 us. 8%) increased (P< 0.05) equally in females and males. These results suggest that the overall increases in concentric and eccentric peak torque and functional strength, in response to short-term accommodated resistance training, occur at a rate that is independent of sex. The torque-velocity relationship, however, appears to change in males suggesting a relatively greater enhancement of maximum voluntary force in the slow-speed, high-force region. Key words : Accommodated resistance, muscular strength, quadriceps peak torque
From previous studies it has been concluded that females and males benefit from short-term resistance training programmes by similar relative increases in lower limb muscle strength (Wilmore 1974, O'Shea & Wegner 1981, Cureton et al. 1988, Weiss et al. 1988). Although these training regimens comprised coupled concentric and eccentric muscle actions, changes in strength were assessed by means of the maximum voluntary contraction (MVC) or the one repetition maximum (1 R M ) techniques. Neither study measured and compared concentric and eccentric strength at various angular velocities. Correspondence : E. B. Colliander, Environmental Physiology Laboratory, Department of Physiology, Box 60 400, Karolinska Institutet, S-104 01 Stockholm, Sweden.
Eccentric peak torque normalized for body weight, is similar but concentric peak torque is lower in females than in males (Colliander & Tesch 1989). Similarly, it has been shown that the ability to utilize elastic energy during jumping activities is greater in females than in males (Komi & Bosco 1978). T h e underlying mechanism(s) for this apparent sex difference is unknown. There are data available, however, to suggest that force generated during a maximum voluntary eccentric muscle action is markedly impaired (Gravel et al. 1987, Triolo et ul. 1987). I f this phenomenon is more pronounced in males it may, at least in part, explain the difference in eccentric relative to concentric strength between females and males. T h e initial increases in muscle strength observed in response to resistance exercise have mainly been attributed
149 6
ACT 141
150
E . B . Colliander and P. A . Tesch
to neural mechanisms (Moritani & deVries 1979)
such as enhanced neural drive ( K o m i 1986) or reduced antagonistic activity (Caiozzo et al. 1981, Hakkinen & Komi 1983). We therefore speculated that males would show greater increase in eccentric strength in response to a short-term resistance training programme which produced substantial increases in strength despite no apparent muscle hypertrophy (Colliander & Tesch 1990). This study therefore compared the effects of a short-term accommodated resistance training programme comprising coupled concentric and eccentric maximum voluntary quadriceps muscle actions in females and males. I t was the purpose to examine changes in performance of concentric and eccentric muscle actions a t various angular velocities a n d functional strength dependent activities.
M A T E R I A L S AND M E T H O D S Subjects
Females ( n = 14) and males ( n = 14) with asymptomatic knee function volunteered for this study. Although physically active they had never participated in regular strength training programmes. T h e habitual activity level of all subjects was maintained during the experimental period. The protocol utilized was approved by the Karolinska Institute Ethics Committee. Subjects gave informed consent and could withdraw their participation at any time during the study. Three females and three males failed to complete the programme due to muscle strains or time constraints. Each group therefore consisted of 11 subjects (Table 1). Seven age-matched males, who did not train, served as controls. They showed no changes in the performance variables measured (see below) over the experimental period (for details see Colliander & Tesch 1990).
Training T h e training programme employed has been described in detail elsewhere (Colliander & Tesch 1990). Briefly, subjects trained three times a week for 12 weeks under supervision. Four to five sets of six maximum bilateral coupled concentric and eccentric muscle actions at a constant angular velocity of 1.05 rad s-' were performed. Each set was followed by a 1.5-2 min rest. From week 4 two male subjects performed unilateral training because of unexpected strength gains resulting in torque outputs interfering with the control of constant angular velocity. Recordings of bilateral were therefore eccentric muscle actions at 0.52 rad SKI
not performed. In addition, four sets of 1&12 repetition maximum (RM) hamstring leg-curls were performed using variable resistance.
Testing Subjects were instructed and acquainted with the training and testing devices and procedures on two occasions prior to the first test. Examinations were made before and after 4, 8 and 12 weeks. The dynamometer (Tesch et ul. 1990) and the procedures (Colliander & Tesch 1989, 1990) used in this study have been described elsewhere. Briefly, the muscle action modes performed were in order: unilateral concentric (UNI(:oN),bilateral concentric (BILl,l)x), unilateral eccentric (UNI Ec(:) and bilateral eccentric (BILM.,r) at constant angular velocities corresponding to 0.52, 1.57 and 2.62 rad S K I .Torque curves were recorded on a strip-chart recorder (Gould 2400, Gould Inc., Cleveland, OH, USA). Peak torque and body weight corrected peak torque were subsequently calculated. Lateral and frontal skinfolds and circumferences of the thigh were measured at one- and two-thirds of the distance between spina iliaca anterior superior and the lateral knee joint line of both limbs. Thereafter, a 10 min warm-up period was followed by measurement of vertical jump height (VJH). Vertical jumps were performed from a deep squatting position with no counter-movement allowed and VJH was defined as the highest value among five trials. Maximum quadriceps muscle actions were then performed and peak torque recorded (see above) and 3 RM half-squat using a barbell was assessed.
Statistics Mean and standard deviation (SD) were calculated and potential intra- and inter-group variations were tested for using analysis of variance (ANOVA). The following model was applied: xLjki= /L +a, B,,L, y r 6, +interaction terms where p = grand mean of test subjects; at=fixed effect of = random group; i = 1 for females, 2 for males, Bj(LJ effect ofsubject within group;; = number ofsubjects; yA.= fixed effect of test; k = 1 for Test 1, 2 for Test 2, 3 for Test 3 and 4 for Test 4, 6, = angular velocity within a muscle-action mode; I = 1 for 0.52 rad s-', 2 for 1.57 rad s-' and 3 for 2.62 rad s-'. Test of simple main effects (Kirk 1981) was used when ANOVA demonstrated statistically significant interaction terms. The level of significance was set at P < 0.05.
+
+ +
RESULTS L i m b skinfold decreased with training in females a n d limb circumference increased in males only (Table 1).
151
Resistance training in jirnales and males Table 1. Physical characteristics of females ( n = 11) and males (n = 11). Values are mean 5 SD. group difference. Females
Age (yrs) Height (cm) Weight (km) Limb skinfold (mm) Limb circumference (cm)
*;
= intra-
Males
Pre
Post
Pre
Post
27+4 16556 57.0+ 6.0 20.9i7.6 52.1 k 3.7
-
26k5 180+3 76.4f6.8 12.2t4.4 54.3k3.7
-
56.4 k 6.8 17.7k5.6' 52.1 k 3.6
-
76.0f6.4 11.2f3.8 54.7+3.9+
Table 2. Unilateral quadriceps peak torque (Nm kg--') and eccentric to concentric ratio in females ( n = 11) = inter-group difference in and males ( n = 11). Values are meanf SD. # = inter-group difference; absolute peak torque increase.
+
Concentric Angular velocity rad .s-'
0.52 1.57 2.62
Females
Males
_ _ _ _ _ _ _ _ _ _ _ _ _~-
- _ _ - - - -- _ _
Pre
Post
Pre
Post
2.51 k0.29 1.99+ 0.18 1.64k0.11
3.17k0.43 2.55 f 0.41 2.04k0.36
2.80f0.32# 2.51 +0.27# 2.11+0.20#
3.80_+0.45# 3.08f0.40# 2.49+0.32#
4.48k0.86 4.41 50.83 4.3050.81
3.46k0.47 3.39 5 0.44 3.18 & 0.56
5.01 k0.82 4.43 + a 7 3 4.10_+0.72
+
Eccentric
0.52 1.57 2.62
3.35+0.54 3.51 f0.59 3.49 k0.57
Eccentric/concentric ratio Females
0.52 1.57 2.62
Males
Pre
Post
Pre
Post
1.34f0.20 1.76f0.23 2.13 k0.34
1.41k0.14 1.73k0.19 2.12t0.28
1.24+ 0.18 1.36k0.19 1.52+0.31#
1.31k0.11 1.44k 0.17 1.65+0.23#
Concentric peak torque, relative to body weight, was greater in males than in females before and after training. Eccentric peak torque was not different between groups (Table 2 & 3). Concentric and eccentric peak torque, regardless of angular velocity, increased with
training in both groups (Table 2 & 3). Absolute increases in UNI,.,, (0.52 rad s-'; Table 2 ) and BIL,,, (all angular velocities; Table 3) were greater in males than in females. The relative increases in peak torque across speeds and muscle action modes were 25(% in females and 6-2
E. B . Colliander and P. A . Tesch
152
T a b l e 3. Bilateral quadriceps peak torque (Nm kg-l) in females (n = 11) and males (n = 11). Values are m e a n i S D . # = inter-group difference; -- inter-group difference in absolute peak torque increase.
+
Concentric Angular velocity
Females
rad.s
Pre
Post
Pre
Post
0.52 1.57 2.62
4.77 k 0.74 4.05f0.50 3.30k0.28
5.96 f0.93 4.80k0.72 3.83k0.56
5.32 k 0.86 4+ 4.66+0.57# 3.9440.41#
7.30 k 0.90 # 5.80f0.71 # 4.74f0.65#
0.52 1.57 2.62
6.2611.38 6.82k1.32 6.50k 1.06
-
650-t 1.32 6.264 1.09 5 . 9 2 4 1.12
-
'
Males
8.18k1.61 8.19f 1.69
+ + +
8.57k 1.58 8.07 1.25
T a b l e 4. Relative increase (%) of uni- and bilateral concentric and eccentric quadriceps peak torque for females (n = 11) and males (n = 11). Values are mean$SD. ~
~
~
~
~
_
_
_
Unilateral Angular velocity
Concentric
Eccentric
rad.s-'
Females
Males
Females
Males
0.52 1.57 2.62
27f 14 2 8 1 16 24k21
37+17 23111 18k8
35k23 27+22 24f17
46 f 23 31+20 31 $28
Bilateral Concentric
0 52 1.57 2.62
Eccentric
Females
Males
Females
Males
2 6 k 11 19f 17 16k 12
39119 26f17 21k15
38k16 21f19 26115
-
32% in males (P> 0.05; Table 4. T h e overall increases in peak torque were greater at 0.52 rad s-l than at 2.62 rad s-'. UNI,,, The absolute increases in (0.52 rad s-'; Fig. 1) and BIL,.,, (all angular velocities), over the four testing sessions, were greater in males than in females. Increases in
39 & 34 39 f27
UNIkccc(Fig. 2) and BILE(,,.were not different between groups. Unilateral concentric peak torque decreased with increasing angular velocity in both groups before training (Fig. 3). This decrease was greater in females than in males before, but not after, training. Independent of sex unilateral
_
Resistance training in females and males
153
E
z
-aJ
I
3
-
F 0
4-
Y
P 200 a
-
L I
0
4
I
I
8
12
weeks Fig. 1. Unilateral concentric quadriceps peak torque (Nm kg-') at 0.52 (0, ),. 1.57 (A, A)and 2.62 (0, W ) rad's for females (open symbols) and males (filled symbols). Values are mean. For differences between mean values and slope of curves see Results.
li
3 a
200
d 0
a
4
12
weeks eccentric peak torque did not change with increasing angular velocity (Fig. 3). In a group comparison, however, males showed greater decrease with increasing angular velocity than females after, but not before, training. Unilateral eccentric/concentric peak torque ratio increased more in females than in males with increasing angular velocity (Table 2). The increase in 3 RM half-squat was similar in females (20%) and males (25%). The corresponding increases in VJH were 10 and 8% respectively (Table 5 ) . DISCUSSION In this study the responses to short-term resistance training were compared in females and males. There were similar relative, overall
Fig. 2. Unilateral eccentric quadriceps peak torque (Nm kg-') at 0.52 (0, ,). 1.57 (A, A)and 2.62 (0, ). rad.s-' for females (open symbols) and males (filled symbols). Values are mean. For differences between mean values and slope of curves see Results.
increases in concentric and eccentric quadriceps peak torque and functional strength, suggesting that the rate of increases in strength dependent performances are not markedly different between sexes. Although this study did not provide conclusive evidences to suggest that increases in concentric or eccentric strength were greater in males than in females, only the former showed a change in the torque-velocity relationship. This was provoked by a greater relative increase in the slow-speed and high-force region.
154
E. B. Colliunder und P. A . Tesch Peak torque INm kg-')
T
ECCENTRIC
CONCENTRIC
t /
I
I
2.62
1.57
I
I
1.57
2.62
I
I
0.52 0.52 Angular velocity (rod
5")
Fig. 3. Unilateral eccentric (left panel) and concentric (right panel) quadriceps peak torque (Nm kg I ) in females (open symbols) and males (filled symbols) before (0, 0 )and after (m, 0) training. Values are mean. For differences between mean values and slope of curves see Results. Table 5. 3 RM half-squat and vertical jump height (VJH) in females (n = 11) and males (n = 11). Values are mean SD. " = intra-group difference.
Females Pre -
3 RM half-squat (kg) VJH (cm)
84+ 14 35.9k5.5
Males Post
_ _
Pre
Post
116+13 45.4k3.9
145+15* 49.0k3.5"
---__
102k 16* 39.3k5.3"
Weekly increases in unilateral concentric and eccentric quadriceps peak torque, across speeds, averaged 2.2 and 2.4% in females and 2.2 and 3.07; in males. T h e corresponding increases for bilateral muscle actions were 1.7 and 2.0% in females and 2.4 and 3.2'% in males. These increases are of similar magnitude to those reported for dynamic (i.e. 1 RM) or isometric lower limb muscle strength in females or males performing resistance training with free weights for 8-16 weeks (Wilmore 1974, Cureton et al. 1988, Weiss et al. 1988). T h e relative gains in concentric and eccentric strength were also comparable to those observed subsequent to concentric, eccentric or coupled concentric and eccentric resistance training in males (Komi & Buskirk 1972, Hakkinen & Komi 1981). Such comparisons should however, be regarded with
caution because the improvements are influenced by the initial state of training and the extent to which the trainees are familiarized to carry out the specific exercises and the test procedure. I n concert with previous reports examining the 1 RM (Wilmore 1974, Cureton et al. 1988) absolute, not relative, overall increases in concentric peak torque across speeds, were greater in males than in females. In contrast, the increase in eccentric peak torque, albeit numerically markedly greater in males, did not differ between females and males. This lack of group difference may simply be explained by the larger variability for eccentric compared to concentric peak torque measurements shown here and noticed elsewhere (Komi & Buskirk 1972, Highgenboten et al. 1988, Colliander & Tesch 1989, Tesch et al. 1990). T h e rate of increase in eccentric peak torque,
Resistance training in -females and males especially at the slowest speed examined, plateaued in females but progressed in males. This suggests that the latter may show a greater increase providing the length of the programme is extended. The enhanced strength demonstrated in response to the present resistance training regimen most likely reflects mainly neural adaptations, because increases in muscle fibre size in the male group were small and non-significant, as already reported (Colliander & Tesch 1990). Similarly, the finding of a small increase in limb girth observed in males and a decreased limb skinfold with no change in circumference in females further imply limited increases in muscle crosssectional area and that the hypertrophic response was similar in females and males. Peak torque during concentric muscle actions decreased with increasing angular velocity (Thorstensson et al. 1976, Perrine & Edgerton 1978). Eccentric peak torque, in contrast, did not vary as a function of angular velocity. Similar results for the quadriceps muscle have previously been reported in males (Westing et al. 1988, Dudley et al. 1989) and females (Westing & Seger 1989) performing unilateral muscle actions. There were, however, evidences of differences in the torque-velocity relationship between males and females. Thus, concentric peak torque showed a greater slope of decrease as a function of increased angular velocity in females before but not after training. This change appeared to be produced by the greater increase in peak torque at low angular velocities in males. Because eccentric but not concentric peak torque relative to body weight, was similar in the two groups the increase in the eccentric to concentric peak torque ratio as a function of increased angular velocity, was greater in females than in males. I t has been suggested that the muscle force generated during the performance of slowspeed, maximum voluntary concentric (Perrine & Edgerton 1978) or eccentric (Gravel et al. 1987, Triolo et ul. 1987) muscle actions is impaired probably through neural inhibitive mechanisms. T h e present findings do suggest that the largest changes in response to training occurred in this part of the torque-velocity curve. I n conclusion, short-term accommodated resistance training comprising maximum concentric and eccentric muscle actions produced marked increases in concentric and eccentric
155
muscle strength in males and females. Although the increases in maximum strength across speeds of concentric and eccentric muscle actions and functional strength were of similar magnitude the torque-velocity relationship appeared to be influenced differently depending on sex. This study was supported by grants from the Royal Swedish Air Force and the Karolinska Institute Research Funds.
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