Physiological functional capacity (PFC) declines at some point with advancing age. Such decrease in PFC has important clinical and functional implications (18,23). Generally, determination of the effect of aging per se on PFC is difficult to perform because several confounding factors (e.g., deconditioning, chronic degenerative disease) could act synergistically and/or independently on the aging process (3). To minimize such confounding influences, one way to assess PFC in humans is to determine the changes in peak sport performances with advancing age of elite athletes (6,21,22).
Master athletes represent an effective study population because age-related changes observed in these healthy trained and motivated athletes are thought to reflect primarily the results of physiological aging. Additionally, elaborate rules and closely monitored competitions ensure well-controlled research environment, from which valuable data can be obtained. Accordingly, a retrospective regression analysis of peak sport performances would provide insight into the functional (performance-based) consequences of declines in muscular strength, muscular endurance, and/or aerobic capacity with advancing age (6,14,15,21,22). Using this approach, we have previously reported that sex and exercise-duration interact to determine the age-related declines in PFC as assessed by running and swimming endurance performance (21,22).
Another, and arguably more important, component of PFC in relation to aging is muscular strength and power. The age-associated decline in peak muscular power generation has important clinical and functional implications for independent living among the elderly (5). The ability to perform many activities of daily living may be compromised by low muscular strength and power even in healthy elderly persons (17), and higher levels of anaerobic muscular power can contribute to high levels of physical function (20). At present, it is not known whether peak strength and power performance declines in similar trend and time courses with advancing age as does peak endurance performance, and whether similar age- and sex-interactions in peak physical performance exist in muscular strength and power. These questions can be addressed effectively using peak physical performance data because these data provide a number of advantages. First, unlike laboratory-based research in which only a limited number of physiological components can be measured, peak lifting performance data would provide integrative changes occurring with age that reflect the sum of many physiological functions. Second, the competitive master lifters are highly motivated and typically train far more intensively than do any subjects enrolled in laboratory-based strength-training interventions. As such, the changes observed in these strength-training athletes may better reflect the effects of “physiological” aging. Third, during the competition, each competitor is striving to have all physiological functions working at their peak and coordinated with the precise timing necessary to perform the required task. It is highly unlikely that older adults in the laboratory settings would ever reach the true maximum effort that is exhibited by master lifters in their competition.
Accordingly, the primary aim of the present investigation was to determine the respective and interactive effects of age and sex on peak anaerobic muscular performance. To accomplish this aim, we performed retrospective analyses of the data compiled from U.S. weightlifting and powerlifting records. We also determined whether more complex and explosive tasks that require a greater involvement of various physiological functions demonstrate greater decreases in PFC with advancing age. To do so, PFC assessed by more complex lifting events (i.e., weightlifting) were compared with simpler lifting events (i.e., powerlifting).
Analyses of weightlifting and powerlifting performance.
Age-group American records for weightlifting and powerlifting were collected from U.S. Weightlifting and Powerlifting Organizations, respectively, and analyzed retrospectively. In both organizations, participants are divided into 5-yr age groups (Table 1). We analyzed snatch and clean & jerk events for weightlifting. The snatch is performed in a continuous movement from the bar on the floor to the fully extended arm position above the head. The clean & jerk involves two separate efforts. The weight is lifted from the platform to the shoulders in one motion (“clean”). The jerk follows with the bar thrust into a position overhead, and then feet are brought together to complete the lift. We also analyzed deadlift, squat, and bench-press events for powerlifting. According to Meltzer (15), body weight or different weight categories do not appear to influence age-related reductions in lifting performance, and we also confirmed such a trend in the present study. The data over the different weight categories were therefore pooled, and overall average age-group values were calculated. However, the age-related changes were calculated within the same weight category. We analyzed the lifting performance records up to the age of 69 yr in both events because only a small number of subjects were available above this age group. We also collected data on the world records in men’s and women’s weightlifting and powerlifting events as of 2002 (International Weightlifting Federation and International Powerlifting Federation, respectively). This allowed us to calculate the rate of age-related decline in performance relative to the world record weight of a particular event.
Regression and correlation analyses were performed to describe the relation between exercise performance and age. A one-way between-subjects analysis of variance (ANOVA) was used to determine differences in lifting events at each age group. In the case of a significant F-value, a post hoc test using Newman-Keuls procedure was used to identify significant differences among mean values. The probability level of statistical significance was set at P < 0.05 in all comparisons. Descriptive statistics were expressed as means ± SE.
Figure 1 illustrates weightlifting and powerlifting performance with advancing age in both women (panel A) and men (panel B). In all the events examined, lifting performance markedly decreased with advancing age. In both sexes, the percent decreases in weightlifting performance (snatch and clean & jerk) were greater (P < 0.05) than those in powerlifting performance (deadlift, squat, and bench press). Differences in age-related declines in muscular strength were not significant between upper body (bench press) and lower body (squat). Similarly, age-related declines were not different between snatch and clean & jerk in weightlifting events.
Sex-related differences in weightlifting and powerlifting performance as function of age are depicted in Figure 2. In weightlifting events (panel A), the magnitude of decline in weightlifting performance (an average of snatch and clean & jerk) in women was markedly greater (P < 0.05) than those in men. The relations between weightlifting records and age were described better with the curvilinear plots (r = −0.99 for women and −0.96 for men) compared with the linear plots (r = −0.93 and −0.94). In contrast to weightlifting events, the rate and magnitude of age-related decline in powerlifting performance (an average of deadlift, squat, and bench press) were not different between men and women (panel B), and the relations between powerlifting performance and age were linear (r = −0.98 for women and −0.99 for men).
The salient findings of the present cross-sectional study are as follows. First, peak anaerobic muscular power, as assessed by peak lifting performance, decreases linearly or curvilinearly, and these decreases begin at an earlier age than was previously thought. Second, the overall magnitude of the decline in peak muscular power appears to be greater in tasks requiring very rapid, highly coordinated movements where exquisite balance must be maintained throughout (i.e., weightlifting events). Third, age-related declines in muscular power are greater in women than in men only in weightlifting events, suggesting that women may experience a greater age-related reduction in tasks that require more explosive and complex movements. Fourth, upper- and lower-body muscular power, as assessed by bench press and squat, demonstrate similar rates of decline with advancing age.
Age-related reductions in PFC can be attributed to the overall decreases in muscular, cardiovascular, and nervous system functions (7,21). Each lifting event is unique in that the extent to which each of the physiological systems is involved differs considerably. We were interested in determining whether more complex and explosive tasks that require a greater involvement of various physiological functions demonstrate greater decreases in PFC with advancing age. To address this, we compared weightlifting and powerlifting performance in terms of the magnitude of reduction in PFC with age. The snatch and clean & jerk in weightlifting events require quickness and explosive power as well as more complex and exquisite neuromuscular coordination to lift the load until the legs and arms are completely straight. It is also critical to possess excellent balance throughout the lift to succeed in these Olympic events. In contrast, speed is not a critical factor for bench press, squat, and deadlift in powerlifting events unlike its name implies, and the movement required in each of the powerlifting events is relatively simple. In the present study, the magnitude of age-related declines in weightlifting performance was substantially greater than that in powerlifting. Our present results are consistent with the previous findings that dynamic muscular power declines at a much faster rate than strength in healthy aging men (16,19,24). Our findings also extend these findings to more dynamic whole-body muscular performance. We could only speculate on the underlying physiological mechanisms, but this may be explained, at least in part, by greater declines in neuromuscular functions and integration, including an incomplete activation of motor units and peripheral nerve dysfunction, that are related to aging (10). Advancing age is also associated with the shift of muscle fiber types from faster to slower myosin heavy chain in both slow and fast muscle fibers (11) as well as decreases in the shortening velocities of all muscle fiber types (11). These age-related changes in muscle contractile properties may also contribute to the greater rate of decline in powerlifting vs weightlifting events. Taken together, these results support the hypothesis that the more complex tasks that require more explosive power and greater neuromuscular coordination may undergo greater reduction with advancing age.
It is interesting to note that greater age-related reductions in PFC were greater in women versus men only in weightlifting events. In contrast, the rate and magnitude of age-related decline in powerlifting performance were not different between men and women. If we were to use the same reasoning applied above, we would hypothesize that women may undergo greater age-related reductions in anaerobic muscular power only in the tasks that require greater involvement of explosive power and complex movement. This is consistent with recent findings that women appear to undergo greater age-related reductions in muscle fiber shortening velocity even at the single fiber levels (10). We cannot exclude the possibility, however, that sociocultural factors may have contributed to these observations (8). For example, it is possible that the explosive nature of weightlifting events may have discouraged more women, particularly older women, to compete in these events, creating what appears to be markedly greater declines in muscular power in female versus male weightlifters.
Previous cross-sectional studies indicate that the declines in muscular strength and power are generally small up to age ∼50 yr and tend to accelerate thereafter (17). Our present results using weightlifting and powerlifting performance do not support this. The reduction in muscular strength and power observed in the present study was rather substantial from young to middle age. The discrepancy between the present and the previous studies may be attributed to the use of more static measures of muscle strength involving smaller muscle mass used by previous investigators. It may be that the decline in more explosive muscular power occurs at accelerated rates starting from a younger age. Consistent with this idea, in both men and women, weightlifting performance declined curvilinearly with advancing age whereas powerlifting performance decreased linearly. More specifically, the decline in muscular performance from young to middle-age was more marked in more explosive weightlifting events than in powerlifting events. It is tempting to hypothesize that more explosive anaerobic muscular power may start to decline at a younger age. We cannot exclude the possibility, however, that because weightlifting is an Olympic event that is sanctioned by the International Olympic Committee, the best records at young elite levels may be elevated higher than those in powerlifting events and therefore had more “room” to decline (i.e., the baseline effect).
In the present study, upper- and lower-body muscular power, as assessed by bench press and squat, demonstrated similar reductions with advancing age. These findings differ from the currently prevalent view that age-associated strength losses occur sooner and at a faster rate in the lower body than in the upper body (1,2). However, in these previous studies, muscular strength was assessed with voluntary isometric contractions. Such findings using static strength tests may not be comparable to those assessing dynamic muscular power. Our present results, using weightlifting and powerlifting performance records, are consistent with more recent studies using an isokinetic dynamometer (13). In the Baltimore Longitudinal study on Aging (13), arm and leg muscle quality derived from the isokinetic dynamometer declined with age at similar rate in healthy men. Taken together, these results suggest that dynamic muscular power, in contrast to static muscular strength, appears to decline similarly in the upper and lower body with advancing age.
Several limitations for the present investigation should be emphasized. First, the effects of aging on PFC in humans have been examined using cross-sectional and longitudinal approaches. The use of cross-sectional comparisons in the present study would be considered a limitation because they may be influenced by genetic and constitutional factors (e.g., cohort difference) (3). However, we and others have demonstrated that well-conducted cross-sectional studies may yield results that are qualitatively similar to those from longitudinal studies when the relation between age and PFC is examined (4,9,14). Second, it is possible that the participation in weightlifting and powerlifting events as well as training practices may have changed over the past decades. If the trends of such changes had been different between men and women or between weightlifting and powerlifting events, it could have affected the age-related rate of decline we observed in the present study. Third, we cannot exclude the possibility that some of the athletes we studied had been using anabolic steroids, growth hormones, or some other muscle building drugs, although both powerlifting and weightlifting agencies have established drug testing procedures to prevent such use. Additionally, the use of nutritional supplementation may have affected the results. Indeed, younger athletes are more likely to adapt performance-enhancing strategies and approaches such as wearing tight body suits, face slapping, and ammonia inhalation, and increasing age might be accompanied by decreasing use of these techniques. This age bias could influence the lifting performance disproportionately across the age range, but the effects of these approaches on performance as well as the incidence of usage in each age group have not been well substantiated.
In summary, our present results add to the growing body of evidence that the decline in PFC with advancing age is gender and task specific (12,22). Moreover, these results provide new information that PFC requiring more powerful and complex tasks undergo greater declines with age and that women appear to experience greater age-related declines in such tasks.
This study was supported in part by National Institutes of Health awards AG-00847 and AG-020966.
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