Eur J Appl Physiol (1990) 61:246-250
European
our..,o, A p p l i e d Physiology and Occupational Physiology © Springer-Verlag 1990
Blood lactate responses in older swimmers during active and passive recovery following maximal sprint swimming Peter R. J. Reaburn and Laurel Traeger Mackinnon Department of Human Movement Studies, University of Queensland, St. Lucia, Queensland 4067, Australia Accepted February 22, 1990
Summary. The purpose of this study was to determine the effect of age on three blood lactate parameters following maximal sprint swimming. The parameters examined were maximal blood lactate concentration, time to reach maximal blood lactate concentration, and half recovery time to baseline lactate concentration. These parameters were examined in 16 male competitive masters swimmers ( n = 4 for each age group: 25-35, 36-45, 46-55, and 56 plus years) during both passive and active recovery following a maximal 100m freestyle sprint. Passive recovery consisted of 60 min sitting in a comfortable chair and active recovery consisted of a 20min swim at a self-selected pace. Capillary blood samples were obtained every 2 min up to 10 min of recovery then at regular intervals to the end of the recovery period. Curves of blood lactate concentration against time were drawn and the three parameters determined for each condition for each subject. There were no significant differences between age groups in any of the lactate parameters examined. A significant difference ( P < 0.05) was noted in each of the parameters between active and passive recovery over all age groups. As expected, active recovery produced lower maximal blood lactate concentrations, lower time to maximal blood lactate values, and lower half recovery times. These data suggest that intensive swimming training may prevent or delay the decline with age in the physiological factors affecting blood lactate values following a maximal sprint swim. Older sprint swimmers appeared to be capable of producing and removing lactic acid at the same rate as younger swimmers. These data suggest that the age-related decline in swim-sprint performance may be due to factors other than changes in anaerobic glycolytic capacity.
Introduction Anaerobic glycolysis provides the major pathway for energy production during maximal exercise lasting 10120 s (Astrand and Rodahl 1986). High muscle and blood lactate concentrations ( > 2 0 m m o l - 1 - 1 ) have been observed in elite sprint swimmers following maximal sprint performance such as a 100 m freestyle swim (Sawka et al. 1979). Since lactic acid (la) accumulation within muscle cells inhibits glycolytic enzymes (Trivedi and Danforth 1966; Karlsson et al. 1974), effective removal of la from previous exercise bouts may be essential for optimal subsequent performance during both competition and training. Removal of la may thus be important during competition Swimming, where an individual may compete in six sprint races within a 6-h period, or during interval sprint training. Previous studies have reported an age-related decrease in maximal la production in runners and cyclists (Robinson et al. 1976; Tzankoff and Norris 1979). The reduced ability to generate la during short term maximal exercise (approximately 60 s) may be related to the decline in sprint performance observed in older athletes (Hartley and Hartley 1984). The purpose of this study was to examine the effect of age on certain blood la parameters following maximal sprint swimming in highly trained male masters swimmers. Parameters of interest were maximal blood lactate concentration ([la]b .... ), time to reach maximal blood lactate concentration (ttlaI. . . . . ), and half recovery time to baseline la level (t 1).
Methods Key words: Aging - Lactate - Swimming
Offprint requests to: P. R. J. Reaburn
Subjects. A group of 16 competitive male masters swimmers were selected with 4 subjects from each of the following age groups: 25=35 years, 36-45 years, 46-55 years and 56 and over. Each was ranked in the top ten for the state of Queensland, Australia, over the 100 m freestyle and all were in the final preparation stages for this event at the World Masters Swimming Championships in Brisbane, Australia, in October, 1988. Training logs were collected
247 and examined to ascertain training volumes and intensities. The project was approved by the University of Queensland Ethics Committee and subjects gave signed informed consent.
Experimental procedure. All testing was carried out in an indoor heated swimming pool 50 m in length with the water temperature standardized at 2 8 - 1 ° C . The study was carried out in two phases. Phase one involved collection of the anthropometric data (height, mass, skinfolds). Skinfold measurements were obtained at eight sites using Harpenden calipers (Pollock et al. 1984). Phase two involved the subject warming up over 400 m freestyle at a self-selected comfortable pace. Three minutes after completion of the warm-up, the subject swam 100 m freestyle at a maximal pace defined as within 5% of each subject's best time of the current season. Beginning 1-min after the maximal exercise bout, the subject either sat in a comfortable chair for 60 min (passive recovery) or swam at a self-selected pace for 20 rain (active recovery). The order of active and passive recovery was randomized and tests were conducted 7-days apart. Blood samples were taken 1-min prior to and 3-min after completion of the warm-up to determine baseline levels. For the passive recovery condition, blood samples were taken immediately after completion of the 100-m freestyle sprint with the subject in the water and then at min 2, 4, 6, 8, 10, 20, 30, 45, and 60 post-exercise. For the active recovery condition, a blood sample was collected immediately following the maximal swim with the subject in the water. The subject then began the active freestyle recovery swim for 20 min with blood samples taken at min 2, 4, 6, 8, 10, 15, and 20 post-exercise. Each blood collection required no more than 30 s. Capillarised blood samples were taken from pre-warmed fingertips using a sterilized lancet puncture to a standardized depth. Samples were collected in a 20 lxl capillary tube with 2 ~tl fluoride ethylenediaminetetraacetate. Samples were centrifuged for 5 rain at 3000 rpm. Supernatant plasma was stored at 4 ° C until lactate analysis within 48 h. Blood samples were assayed by an enzymatic (UV) method modified by Noll (1974) using an IL Microstat 111 micro centrifuge analyser (Instrumentation Laboratory, Spokane, WA, USA).
iance (ANOVA) was undertaken to determine statistically significant effects of age and recovery condition on each of the blood la parameters examined. Regressions of each la parameter and recovery condition on age were also undertaken using a Unix Labtam Computer System, Labtam Information Systems P/L, Melbourne, Australia. An estimation of the reduction in residual errors was undertaken to determine significant differences between the curves for each condition. A P level of 0.05 was accepted as showing statistical significance.
Results A n a l y s i s of the t r a i n i n g logs s h o w e d n o age-related differences in t r a i n i n g i n t e n s i t y a n d v o l u m e (data n o t shown). T a b l e 1 presents the p h y s i o l o g i c a l a n d perf o r m a n c e data ( m e a n s a n d ranges) for each of the age g r o u p s e x a m i n e d . A progressive i n c r e a s e in best rec o r d e d 100-m s w i m m i n g time was o b s e r v e d with increasing age. Tables 2 a n d 3 p r e s e n t the m e a n s a n d s t a n d a r d d e v i a t i o n s for each o f the lab p a r a m e t e r s exa m i n e d for passive a n d active recovery, respectively. N o effect o f age was n o t e d for a n y of the p a r a m e t e r s e x a m i n e d t a k e n over b o t h recovery c o n d i t i o n s w h e n d a t a are g r o u p e d b y the f o u r age groups. The regression a n a l y s i s o n age p r o d u c e d n o statistically s i g n i f i c a n t t r e n d s for age o n a n y o f the p a r a m e t e r s i n either recovery c o n d i t i o n . A n a l y s i s o f v a r i a n c e i n d i c a t e d a s i g n i f i c a n t effect o f r e c o v e r y c o n d i t i o n for each age g r o u p e x a m i n e d . T h e active r e c o v e r y c o n d i t i o n p r o d u c e d a l o w e r [la]b. . . . ( P < 0 . 0 5 ) , lower tBa]. . . . . ( P < 0 . 0 5 ) , a n d l o w e r t l ( P < 0.001) t h a n the passive recovery c o n d i t i o n across all age groups. T h e m e a n active r e c o v e r y p a c e t a k e n over all subjects was 63.6%, SD 4.6% o f m a x i m a l 100 m freestyle pace.
Statistical analysis. The parameters of interest w e r e [la]b . . . . . ttlaJ...... and t~. In the absence of a reliable non-linear regression technique to calculate these values, lines of best fit of blood la values against time were drawn by eye according to McLennan and Skinner (1982). From these curves, values for the above parameters were obtained. Means and standard deviations for each of the parameters for each age group were determined in both the passive and active recovery conditions. Two-way analysis of var-
Discussion The results of this study indicate that the three b l o o d la parameters e x a m i n e d ([la]b. . . . . ttla]. . . . . . a n d t l ) s h o w e d n o s i g n i f i c a n t t r e n d for age in either the active or pas-
Table 1. Physiological and performance characteristics of subjects a Age group b (years)
Age (years)
Height (cm)
Body mass (kg)
Skinfold totaF (mm)
Swim time d (s)
25-35
31.3 (28-34) 41.0 (39-44) 49.5 (46-53) 67.0 (58-80)
182.7 (169-191) 174.5 ( 169-181) 171.4 (168-173) 172.9 (166-177)
78.1 (67.0-86.0) 73.3 (61.0- 82.0) 73.3 (72.0-75.0) 74.8 (70.5-81.0)
55.2 (45.6-68.8) 73.8 (41.3-89.1 ) 70.1 (65.4-81.4) 83.8 (62.8-113.8)
59.6 (57.6-60.4) 65.9 (60.5-69.3) 71.7 (68.1-78.0) 96.7 (77.0-130.0)
36-45 46-55 56 plus a b c a
Values are means with range in parentheses n, 4 for each age group Sum of skinfolds from eight sites (triceps, biceps, mid-axillary, subscapular, supra-iliac, abdominal, thigh, calf) 100 m freestyle swim at maximal pace (recorded during study)
248 Table 2. Blood lactate (la) parameters in male masters swimmers during passive recovery following a maximal 100m freestyle swim Age group (years) Parameter
25-35 n=4
36-45 n =4
46-55 n=4
56 plus n=4
[la]b.... (mmol- 1- a) tt~a~...... (min) t~
mean SD mean SD mean SD
14.25 3.34 5.95 2.33 24.65 8.89
15.00 1.28 9.30 2.50 34.23 5.12
15.35 2.41 7.10 0.89 29.83 8.46
(min)
13.05 4.97 6.80 0.86 20.55 4.20
[la]b . . . . .
Maximal blood lactate concentration; t[la]h .... , time to [la]b.... ; ta, half recovery time equals time to reach (½ [la]b.... resting la)
Table 3. Blood lactate (la) parameters in male masters swimmers during active recovery following a maximal 100 m freestyle swim Age group (years) Parameter
25-35 n =4
36-45 n =4
46-55 n =4
56 plus n =4
[la]b . . . . .
mean SD mean SD mean SD
11.90 2.68 5.10 1.32 12.55 2.03
14.30 2.39 5.50 2.27 21.75 3.34
14.10 4.32 4.95 2.56 16.23 6.17
(mmol. 1-1) t0aI...... (min) t~ (min)
11.93 2.63 4.90 0.82 17.55 3.62
For definitions see Table 2
sive recovery conditions. These results are consistent with the work of Wahren et al. (1974) who noted no age related differences in the rate of la release from muscle to blood in cyclists following incremental maximal exercise. The lack of an effect of age on these blood la parameters suggests that in older male swimmers the ability to produce, translocate, and remove la may be maintained by continued high intensity training. Previous research on elite endurance runners has suggested that during aging there is a decrease in [la]b. . . . from 15 m m o l . 1 - 1 at age 25 years to 11 mmol.1 -~ in 56 yearold and older runners (Robinson et al. 1976). In the current study on sprint swimmers, [la]b. . . . values of 14.25 mmol.1-1, SD 3.34 were observed in 25-35 yearolds and 13.05 m m o l . l -~, SD 4.97 in 56 year-olds and older swimmers with no significant difference noted between the two groups. It is of interest that the maximal swimming times to produce these [la]b. . . . values were 59.6 and 96.7 s in the youngest and oldest groups, respectively. It could be argued that the older swimmers may have had a greater relative energy contribution from the aerobic energy system compared to the anaerobic system. However, available evidence (Astrand
and Rodahl 1986; Lamb 1984) suggests that the relative energy contribution from the aerobic and anaerobic systems are similar over periods of 60-90 s. Previous research on runners has also shown an increase in t[lal. . . . . with age - 3 min iff 20-30 year-olds, 5 min in 31-40 year-olds, and 7 min in 50-60 year-old sedentary males during passive recovery following an incremental endurance treadmill run to exhaustion (Tzankoff and Norris 1979). The results of the current study are not consistent with these previous findings; values of 5.95 min, SD 2.33 were noted in 25-35 yearolds and 6.80 rain, SD 0.86 in over 56 year-old swimmers. The differences noted between the studies in peak blood la concentration and trial..... may be due to the different types of testing protocols and the subjects used in both the previous studies (Robinson et al. 1976, Tzankoff and Norris 1979). In these earlier studies reporting age-related declines in [la]b. . . . values, maximal endurance testing was used to elicit [la]b. . . . in both endurance runners and sedentary subjects. The present data were obtained following sprinting in sprint-trained swimmers. It would appear from the data presented here that high intensity sprint-training in older male swimmers may maintain the ability to generate high blood la and to maintain high rates of la translocation from muscle to blood and removal of la from the circulation. Although no statistical significance was observed among the age groups, the tVaI..... and tl for the 36-45 year-old age group were noticably higher than in the other three age groups. Within this age grouP 2 of the 4 subjects recorded higher than average values for both of these parameters. It could be speculated that in these subjects lower intramuscular blood flow past the la producing muscle fibres may slow la removal and contribute to the higher values recorded for ttlaI..... value during passive recovery (Table 2) and the higher tl r e corded for both passive and active recovery (Tables 2, 3). However, since in the two older age groups (46-55 years and over 56 years) all la parameters were similar to those observed in the youngest group (25-35 years), this does not appear to be a trend with age. Previous research has identified several possible factors contributing to the suggested age-related decline in la production and removal - a decrease in muscle mass (Lexell et al. 1983), a decrease in glycolytic fast-twitch fibre area (Grimby and Saltin 1983), a preferential loss in the number of fast-twitch fibres (Larsson 1978), a decrease in the number of motor units (Campbell et al. 1973), and decreased i n t r a m u s c u l a r blood flow (Wahren et al. 1974). It is possible that the ability to generate high blood la observed in these swimmers is due to the maintenance of some or all of the factors listed above as a result of continued sprint training. For example, high intensity sprint training may facilitate maintenance of, or slow the decline in, total muscle mass a n d / o r fast twitch fibre size and number. Since total glycolytic potential appears to be related to total muscle mass and specifically fast twitch
249 fibre size and n u m b e r (Tesch et al. 1978), sprint training during aging m a y thus facilitate maintenance of glycolytic potential. This suggestion is supported by the work of Suominen and others (1980) who found higher fast twitch fibre areas in habitually-trained aged endurancerunners as c o m p a r e d to age-matched sedentary controis, as well as a study that noted increases in lactic dehydrogenase activity by as much as 49'% following training in older individuals (Orlander and Aniansson 1980). High intensity training m a y also prevent or lessen the decline in n u m b e r of m o t o r units observed with increasing age (Campbell et al. 1973). However, the observation of an apparent age-related decrease in total muscle mass in the older swimmers, as evidenced by a progressive decline in total b o d y mass and increase in total skinfold thickness (Table 1), would tend to suggest there had been some loss of muscle mass with age despite high intensity training. The hypothesized trend of a longer t l with increasing age was not observed. This suggestion was based on several previous reports of decreased intramuscular blood flow with age (Wahren et al. 1974) and slower rates of la diffusion across cell m e m b r a n e s (Tzankoff and Norris 1979). The results of the present study suggested that continued intensive training may, at least partially, have prevented some of these age-related decreases observed in sedentary populations. The finding that active recovery after sprint swimming resulted in significantly lower tl c o m p a r e d to passive recovery is consistent with previous research (Belcastro and Bonen 1975; McLellan and Skinner 1982). These authors noted t 1 for active recovery at 40% maximal oxygen uptake (VO2max) of 10--14 min in young healthy adults following a one mile run (Belcastro and Bonen 1975) and 10 min of cycling to exhaustion (McLellan and Skinner 1982). In the current study, values of between 12.55 min, SD 2.03 and 21.75 min, SD 3.34 were observed. In previous reports using endurance exercise, [la]b. . . . of 11-12 m m o l - 1 - 1 for the run (Belcastro and Bonen 1975) and 8-9 m m o l . l - a for cycling (Mclellan and Skinner 1982) were reported. These values are lower than the values obtained in the current study, possibly due to the higher aerobic contribution to p e r f o r m a n c e in the previous studies. Alternatively, the intensity of exercise utilized in recovery in the current study, approximately 60%VO2 . . . . m a y have slightly increased la production and c o m p r o m i s e d la removal, thus leading to the longer t~ noted. The use of a self-selected pace in active recovery in this study was based on previous research suggesting that swimmers can self-select a pace, equivalent to 60%-70% of maximal 100-m pace, for optimal la removal (Cazorla et al. 1983). The m e a n self-selected recovery pace n o t e d in the current study for all age groups was 63.6%, SD 4.6% of maximal 100-m pace. This pace is consistent with previous work on runners and cyclists who also a p p e a r able to self-select a recov-
ery pace to maximize la removal (Belcastro and Bonen 1975; Bonen and Belcastro 1976). In conclusion, the results of this study suggest that certain lab parameters ([la]b . . . . . t0alb. . . . and tl m a y be maintained with high-intensity sprint-swim training as age increases. The ability to generate and remove la from muscle does not a p p e a r to explain decreased sprint p e r f o r m a n c e in older competitive swimmers (Hartley and Hartley 1984). It would a p p e a r that other factors such as changes in total muscle mass, declines in strength, alterations in neuromuscular function, motivational, or other factors, m a y contribute more to the observed decline in sprint-swimming p e r f o r m a n c e than the ability to generate and remove la.
Acknowledgements. We acknowledge the generous support of this project by the Queensland and Australian Masters Swimming Associations and the invaluable assistance of Dr. Alf Howard with the statistical analysis.
References Astrand P-O, Rodahl K (1986) Textbook of Work Physiology. McGraw-Hill, New York Belcastro AN, Bonen A (1975) Lactic acid removal rates during controlled and uncontrolled recovery exercise. J Appl Physiol 39:932-936 Bonen A, Belcastro A (1976) Comparison of self selected recovery methods on lactic acid removal rates. Med Sci Sports 8:176178 Campbell MJ, McComas AJ, Petito F (1973) Physiological changes in aging muscles. J Neurol Neurosurg Psychiatry 36:174-182 Cazorla G, Dufort C, Cervetti JP, Montpetit RR (1983) The influence of active recovery on blood lactate disappearance after supramaximal swimming. In: Hollander AP, Huijing PA, De Groot G (eds) Biomechanics and medicine in swimming. Human Kinetics, Champaign, Ill, pp 244-250 Grimby G, Saltin B (1983) The aging muscle. Clin Physiol 3:209218 Hartley AA, Hartley JT (1984) Performance changes in champion swimmers aged 30 to 84 years. Exp Aging Res 10:141-147 Karlsson J, Hulten B, Sjodin B (1974) Substrate activation and product inhibition of LDH activity in human skeletal muscle. Acta Physiol Scand 92:21-26 Lamb DR (1984) Physiology of exercise. Responses and adaptions. Macmillan, New York Larsson L (1978) Morphological and functional characteristics of the aging skeletal muscle in man. Acta Physiol Scand [Suppl] 457:1-36 Lexell J, Henriksson-Larsen K, Winblad B, Sjostrom M (1983) Distribution of different fibre types in human skeletal muscles: effects of aging studied in whole muscle cross sections. Muscle Nerve 6:588-595 McLellan TM, Skinner JS (1982) Blood lactate removal during active recovery related to the aerobic threshold. Int J Sports Med 3:224-229 Noll F (1974) L(+) - lactate determination with LDH, GPT and NAD. In: Bergmeyer HU (ed) Methods of enzymatic analysis (2nd edn.). Academic Press, New York, p 1475 ff. Orlander J, Aniansson A (1980) Effects of physical training on skeletal muscle metabolism and ultrastructure in 70 to 75 year old men. Acta Physiol Scand 109:149-154 Pollock ML, Wilmore JH, Fox SM (1984) Exercise in health and disease: evaluation and prescription for prevention and rehabilitation. Saunders, Philadelphia
250 Robinson S, Dill DB, Robinson RD, Tzankoff SP, Wagner JA (1976) Physiological aging of champion runners. J Appl Physiol 41:46-51 Sawka MN, Knowlton RG, Miles DS, Critz JB (1979) Post competition blood lactate concentrations in collegiate swimmers. Eur J Appl Physiol 41:93-99 Suominen H, Heikkinen E, Parkatti T, Forsberg S, Kiiskinen A (1980) Effects of "lifelong" physical training on functional aging in men. Scand J Soc Med [Suppl] 14:225-240 Tesch P, Sjodin B, Karlsson J (1978) Relationship between lactate accumulation, LDH activity, LDH isozyme and fibre type dis-
tribution in human skeletal muscle. Acta Physiol Scand 103 :40-46 Trivedi B, Danforth WH (1966) Effect of pH on the kinetics of frog muscle phosphofructokinase. J Biol Chem 241:41104114 Tzankoff SP, Norris AH (1979) Age-related differences in lactate distribution kinetics following maximal exercise. Eur J Appl Physiol 42: 35-40 Wahren J, Saltin B, Jorfeldt L, Pernow B (1974) Influence of age on the local circulatory adaption to leg exercise. Scand J Clin Lab Invest 33:79-86
European
our..,o, A p p l i e d Physiology and Occupational Physiology © Springer-Verlag 1990
Blood lactate responses in older swimmers during active and passive recovery following maximal sprint swimming Peter R. J. Reaburn and Laurel Traeger Mackinnon Department of Human Movement Studies, University of Queensland, St. Lucia, Queensland 4067, Australia Accepted February 22, 1990
Summary. The purpose of this study was to determine the effect of age on three blood lactate parameters following maximal sprint swimming. The parameters examined were maximal blood lactate concentration, time to reach maximal blood lactate concentration, and half recovery time to baseline lactate concentration. These parameters were examined in 16 male competitive masters swimmers ( n = 4 for each age group: 25-35, 36-45, 46-55, and 56 plus years) during both passive and active recovery following a maximal 100m freestyle sprint. Passive recovery consisted of 60 min sitting in a comfortable chair and active recovery consisted of a 20min swim at a self-selected pace. Capillary blood samples were obtained every 2 min up to 10 min of recovery then at regular intervals to the end of the recovery period. Curves of blood lactate concentration against time were drawn and the three parameters determined for each condition for each subject. There were no significant differences between age groups in any of the lactate parameters examined. A significant difference ( P < 0.05) was noted in each of the parameters between active and passive recovery over all age groups. As expected, active recovery produced lower maximal blood lactate concentrations, lower time to maximal blood lactate values, and lower half recovery times. These data suggest that intensive swimming training may prevent or delay the decline with age in the physiological factors affecting blood lactate values following a maximal sprint swim. Older sprint swimmers appeared to be capable of producing and removing lactic acid at the same rate as younger swimmers. These data suggest that the age-related decline in swim-sprint performance may be due to factors other than changes in anaerobic glycolytic capacity.
Introduction Anaerobic glycolysis provides the major pathway for energy production during maximal exercise lasting 10120 s (Astrand and Rodahl 1986). High muscle and blood lactate concentrations ( > 2 0 m m o l - 1 - 1 ) have been observed in elite sprint swimmers following maximal sprint performance such as a 100 m freestyle swim (Sawka et al. 1979). Since lactic acid (la) accumulation within muscle cells inhibits glycolytic enzymes (Trivedi and Danforth 1966; Karlsson et al. 1974), effective removal of la from previous exercise bouts may be essential for optimal subsequent performance during both competition and training. Removal of la may thus be important during competition Swimming, where an individual may compete in six sprint races within a 6-h period, or during interval sprint training. Previous studies have reported an age-related decrease in maximal la production in runners and cyclists (Robinson et al. 1976; Tzankoff and Norris 1979). The reduced ability to generate la during short term maximal exercise (approximately 60 s) may be related to the decline in sprint performance observed in older athletes (Hartley and Hartley 1984). The purpose of this study was to examine the effect of age on certain blood la parameters following maximal sprint swimming in highly trained male masters swimmers. Parameters of interest were maximal blood lactate concentration ([la]b .... ), time to reach maximal blood lactate concentration (ttlaI. . . . . ), and half recovery time to baseline la level (t 1).
Methods Key words: Aging - Lactate - Swimming
Offprint requests to: P. R. J. Reaburn
Subjects. A group of 16 competitive male masters swimmers were selected with 4 subjects from each of the following age groups: 25=35 years, 36-45 years, 46-55 years and 56 and over. Each was ranked in the top ten for the state of Queensland, Australia, over the 100 m freestyle and all were in the final preparation stages for this event at the World Masters Swimming Championships in Brisbane, Australia, in October, 1988. Training logs were collected
247 and examined to ascertain training volumes and intensities. The project was approved by the University of Queensland Ethics Committee and subjects gave signed informed consent.
Experimental procedure. All testing was carried out in an indoor heated swimming pool 50 m in length with the water temperature standardized at 2 8 - 1 ° C . The study was carried out in two phases. Phase one involved collection of the anthropometric data (height, mass, skinfolds). Skinfold measurements were obtained at eight sites using Harpenden calipers (Pollock et al. 1984). Phase two involved the subject warming up over 400 m freestyle at a self-selected comfortable pace. Three minutes after completion of the warm-up, the subject swam 100 m freestyle at a maximal pace defined as within 5% of each subject's best time of the current season. Beginning 1-min after the maximal exercise bout, the subject either sat in a comfortable chair for 60 min (passive recovery) or swam at a self-selected pace for 20 rain (active recovery). The order of active and passive recovery was randomized and tests were conducted 7-days apart. Blood samples were taken 1-min prior to and 3-min after completion of the warm-up to determine baseline levels. For the passive recovery condition, blood samples were taken immediately after completion of the 100-m freestyle sprint with the subject in the water and then at min 2, 4, 6, 8, 10, 20, 30, 45, and 60 post-exercise. For the active recovery condition, a blood sample was collected immediately following the maximal swim with the subject in the water. The subject then began the active freestyle recovery swim for 20 min with blood samples taken at min 2, 4, 6, 8, 10, 15, and 20 post-exercise. Each blood collection required no more than 30 s. Capillarised blood samples were taken from pre-warmed fingertips using a sterilized lancet puncture to a standardized depth. Samples were collected in a 20 lxl capillary tube with 2 ~tl fluoride ethylenediaminetetraacetate. Samples were centrifuged for 5 rain at 3000 rpm. Supernatant plasma was stored at 4 ° C until lactate analysis within 48 h. Blood samples were assayed by an enzymatic (UV) method modified by Noll (1974) using an IL Microstat 111 micro centrifuge analyser (Instrumentation Laboratory, Spokane, WA, USA).
iance (ANOVA) was undertaken to determine statistically significant effects of age and recovery condition on each of the blood la parameters examined. Regressions of each la parameter and recovery condition on age were also undertaken using a Unix Labtam Computer System, Labtam Information Systems P/L, Melbourne, Australia. An estimation of the reduction in residual errors was undertaken to determine significant differences between the curves for each condition. A P level of 0.05 was accepted as showing statistical significance.
Results A n a l y s i s of the t r a i n i n g logs s h o w e d n o age-related differences in t r a i n i n g i n t e n s i t y a n d v o l u m e (data n o t shown). T a b l e 1 presents the p h y s i o l o g i c a l a n d perf o r m a n c e data ( m e a n s a n d ranges) for each of the age g r o u p s e x a m i n e d . A progressive i n c r e a s e in best rec o r d e d 100-m s w i m m i n g time was o b s e r v e d with increasing age. Tables 2 a n d 3 p r e s e n t the m e a n s a n d s t a n d a r d d e v i a t i o n s for each o f the lab p a r a m e t e r s exa m i n e d for passive a n d active recovery, respectively. N o effect o f age was n o t e d for a n y of the p a r a m e t e r s e x a m i n e d t a k e n over b o t h recovery c o n d i t i o n s w h e n d a t a are g r o u p e d b y the f o u r age groups. The regression a n a l y s i s o n age p r o d u c e d n o statistically s i g n i f i c a n t t r e n d s for age o n a n y o f the p a r a m e t e r s i n either recovery c o n d i t i o n . A n a l y s i s o f v a r i a n c e i n d i c a t e d a s i g n i f i c a n t effect o f r e c o v e r y c o n d i t i o n for each age g r o u p e x a m i n e d . T h e active r e c o v e r y c o n d i t i o n p r o d u c e d a l o w e r [la]b. . . . ( P < 0 . 0 5 ) , lower tBa]. . . . . ( P < 0 . 0 5 ) , a n d l o w e r t l ( P < 0.001) t h a n the passive recovery c o n d i t i o n across all age groups. T h e m e a n active r e c o v e r y p a c e t a k e n over all subjects was 63.6%, SD 4.6% o f m a x i m a l 100 m freestyle pace.
Statistical analysis. The parameters of interest w e r e [la]b . . . . . ttlaJ...... and t~. In the absence of a reliable non-linear regression technique to calculate these values, lines of best fit of blood la values against time were drawn by eye according to McLennan and Skinner (1982). From these curves, values for the above parameters were obtained. Means and standard deviations for each of the parameters for each age group were determined in both the passive and active recovery conditions. Two-way analysis of var-
Discussion The results of this study indicate that the three b l o o d la parameters e x a m i n e d ([la]b. . . . . ttla]. . . . . . a n d t l ) s h o w e d n o s i g n i f i c a n t t r e n d for age in either the active or pas-
Table 1. Physiological and performance characteristics of subjects a Age group b (years)
Age (years)
Height (cm)
Body mass (kg)
Skinfold totaF (mm)
Swim time d (s)
25-35
31.3 (28-34) 41.0 (39-44) 49.5 (46-53) 67.0 (58-80)
182.7 (169-191) 174.5 ( 169-181) 171.4 (168-173) 172.9 (166-177)
78.1 (67.0-86.0) 73.3 (61.0- 82.0) 73.3 (72.0-75.0) 74.8 (70.5-81.0)
55.2 (45.6-68.8) 73.8 (41.3-89.1 ) 70.1 (65.4-81.4) 83.8 (62.8-113.8)
59.6 (57.6-60.4) 65.9 (60.5-69.3) 71.7 (68.1-78.0) 96.7 (77.0-130.0)
36-45 46-55 56 plus a b c a
Values are means with range in parentheses n, 4 for each age group Sum of skinfolds from eight sites (triceps, biceps, mid-axillary, subscapular, supra-iliac, abdominal, thigh, calf) 100 m freestyle swim at maximal pace (recorded during study)
248 Table 2. Blood lactate (la) parameters in male masters swimmers during passive recovery following a maximal 100m freestyle swim Age group (years) Parameter
25-35 n=4
36-45 n =4
46-55 n=4
56 plus n=4
[la]b.... (mmol- 1- a) tt~a~...... (min) t~
mean SD mean SD mean SD
14.25 3.34 5.95 2.33 24.65 8.89
15.00 1.28 9.30 2.50 34.23 5.12
15.35 2.41 7.10 0.89 29.83 8.46
(min)
13.05 4.97 6.80 0.86 20.55 4.20
[la]b . . . . .
Maximal blood lactate concentration; t[la]h .... , time to [la]b.... ; ta, half recovery time equals time to reach (½ [la]b.... resting la)
Table 3. Blood lactate (la) parameters in male masters swimmers during active recovery following a maximal 100 m freestyle swim Age group (years) Parameter
25-35 n =4
36-45 n =4
46-55 n =4
56 plus n =4
[la]b . . . . .
mean SD mean SD mean SD
11.90 2.68 5.10 1.32 12.55 2.03
14.30 2.39 5.50 2.27 21.75 3.34
14.10 4.32 4.95 2.56 16.23 6.17
(mmol. 1-1) t0aI...... (min) t~ (min)
11.93 2.63 4.90 0.82 17.55 3.62
For definitions see Table 2
sive recovery conditions. These results are consistent with the work of Wahren et al. (1974) who noted no age related differences in the rate of la release from muscle to blood in cyclists following incremental maximal exercise. The lack of an effect of age on these blood la parameters suggests that in older male swimmers the ability to produce, translocate, and remove la may be maintained by continued high intensity training. Previous research on elite endurance runners has suggested that during aging there is a decrease in [la]b. . . . from 15 m m o l . 1 - 1 at age 25 years to 11 mmol.1 -~ in 56 yearold and older runners (Robinson et al. 1976). In the current study on sprint swimmers, [la]b. . . . values of 14.25 mmol.1-1, SD 3.34 were observed in 25-35 yearolds and 13.05 m m o l . l -~, SD 4.97 in 56 year-olds and older swimmers with no significant difference noted between the two groups. It is of interest that the maximal swimming times to produce these [la]b. . . . values were 59.6 and 96.7 s in the youngest and oldest groups, respectively. It could be argued that the older swimmers may have had a greater relative energy contribution from the aerobic energy system compared to the anaerobic system. However, available evidence (Astrand
and Rodahl 1986; Lamb 1984) suggests that the relative energy contribution from the aerobic and anaerobic systems are similar over periods of 60-90 s. Previous research on runners has also shown an increase in t[lal. . . . . with age - 3 min iff 20-30 year-olds, 5 min in 31-40 year-olds, and 7 min in 50-60 year-old sedentary males during passive recovery following an incremental endurance treadmill run to exhaustion (Tzankoff and Norris 1979). The results of the current study are not consistent with these previous findings; values of 5.95 min, SD 2.33 were noted in 25-35 yearolds and 6.80 rain, SD 0.86 in over 56 year-old swimmers. The differences noted between the studies in peak blood la concentration and trial..... may be due to the different types of testing protocols and the subjects used in both the previous studies (Robinson et al. 1976, Tzankoff and Norris 1979). In these earlier studies reporting age-related declines in [la]b. . . . values, maximal endurance testing was used to elicit [la]b. . . . in both endurance runners and sedentary subjects. The present data were obtained following sprinting in sprint-trained swimmers. It would appear from the data presented here that high intensity sprint-training in older male swimmers may maintain the ability to generate high blood la and to maintain high rates of la translocation from muscle to blood and removal of la from the circulation. Although no statistical significance was observed among the age groups, the tVaI..... and tl for the 36-45 year-old age group were noticably higher than in the other three age groups. Within this age grouP 2 of the 4 subjects recorded higher than average values for both of these parameters. It could be speculated that in these subjects lower intramuscular blood flow past the la producing muscle fibres may slow la removal and contribute to the higher values recorded for ttlaI..... value during passive recovery (Table 2) and the higher tl r e corded for both passive and active recovery (Tables 2, 3). However, since in the two older age groups (46-55 years and over 56 years) all la parameters were similar to those observed in the youngest group (25-35 years), this does not appear to be a trend with age. Previous research has identified several possible factors contributing to the suggested age-related decline in la production and removal - a decrease in muscle mass (Lexell et al. 1983), a decrease in glycolytic fast-twitch fibre area (Grimby and Saltin 1983), a preferential loss in the number of fast-twitch fibres (Larsson 1978), a decrease in the number of motor units (Campbell et al. 1973), and decreased i n t r a m u s c u l a r blood flow (Wahren et al. 1974). It is possible that the ability to generate high blood la observed in these swimmers is due to the maintenance of some or all of the factors listed above as a result of continued sprint training. For example, high intensity sprint training may facilitate maintenance of, or slow the decline in, total muscle mass a n d / o r fast twitch fibre size and number. Since total glycolytic potential appears to be related to total muscle mass and specifically fast twitch
249 fibre size and n u m b e r (Tesch et al. 1978), sprint training during aging m a y thus facilitate maintenance of glycolytic potential. This suggestion is supported by the work of Suominen and others (1980) who found higher fast twitch fibre areas in habitually-trained aged endurancerunners as c o m p a r e d to age-matched sedentary controis, as well as a study that noted increases in lactic dehydrogenase activity by as much as 49'% following training in older individuals (Orlander and Aniansson 1980). High intensity training m a y also prevent or lessen the decline in n u m b e r of m o t o r units observed with increasing age (Campbell et al. 1973). However, the observation of an apparent age-related decrease in total muscle mass in the older swimmers, as evidenced by a progressive decline in total b o d y mass and increase in total skinfold thickness (Table 1), would tend to suggest there had been some loss of muscle mass with age despite high intensity training. The hypothesized trend of a longer t l with increasing age was not observed. This suggestion was based on several previous reports of decreased intramuscular blood flow with age (Wahren et al. 1974) and slower rates of la diffusion across cell m e m b r a n e s (Tzankoff and Norris 1979). The results of the present study suggested that continued intensive training may, at least partially, have prevented some of these age-related decreases observed in sedentary populations. The finding that active recovery after sprint swimming resulted in significantly lower tl c o m p a r e d to passive recovery is consistent with previous research (Belcastro and Bonen 1975; McLellan and Skinner 1982). These authors noted t 1 for active recovery at 40% maximal oxygen uptake (VO2max) of 10--14 min in young healthy adults following a one mile run (Belcastro and Bonen 1975) and 10 min of cycling to exhaustion (McLellan and Skinner 1982). In the current study, values of between 12.55 min, SD 2.03 and 21.75 min, SD 3.34 were observed. In previous reports using endurance exercise, [la]b. . . . of 11-12 m m o l - 1 - 1 for the run (Belcastro and Bonen 1975) and 8-9 m m o l . l - a for cycling (Mclellan and Skinner 1982) were reported. These values are lower than the values obtained in the current study, possibly due to the higher aerobic contribution to p e r f o r m a n c e in the previous studies. Alternatively, the intensity of exercise utilized in recovery in the current study, approximately 60%VO2 . . . . m a y have slightly increased la production and c o m p r o m i s e d la removal, thus leading to the longer t~ noted. The use of a self-selected pace in active recovery in this study was based on previous research suggesting that swimmers can self-select a pace, equivalent to 60%-70% of maximal 100-m pace, for optimal la removal (Cazorla et al. 1983). The m e a n self-selected recovery pace n o t e d in the current study for all age groups was 63.6%, SD 4.6% of maximal 100-m pace. This pace is consistent with previous work on runners and cyclists who also a p p e a r able to self-select a recov-
ery pace to maximize la removal (Belcastro and Bonen 1975; Bonen and Belcastro 1976). In conclusion, the results of this study suggest that certain lab parameters ([la]b . . . . . t0alb. . . . and tl m a y be maintained with high-intensity sprint-swim training as age increases. The ability to generate and remove la from muscle does not a p p e a r to explain decreased sprint p e r f o r m a n c e in older competitive swimmers (Hartley and Hartley 1984). It would a p p e a r that other factors such as changes in total muscle mass, declines in strength, alterations in neuromuscular function, motivational, or other factors, m a y contribute more to the observed decline in sprint-swimming p e r f o r m a n c e than the ability to generate and remove la.
Acknowledgements. We acknowledge the generous support of this project by the Queensland and Australian Masters Swimming Associations and the invaluable assistance of Dr. Alf Howard with the statistical analysis.
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