Age and gender interactions in physiological functional capacity: insight from swimming performance

Tanaka, Hirofumi, and Douglas R. Seals. Age and genderinteractions in physiological functional capacity: insight from swimming performance. J. Appl.Physiol. 82(3): 846-851, 1997.One experimentalapproach to studying the effects of aging on physiological functionalcapacity in humans is to analyze the peak exercise performance ofhighly trained athletes with increasing age. To gain insight into therelationships among age, gender, and exercise task duration with use ofthis model, we performed a 5-yr (1991-1995) retrospective analysisof top freestyle performance times from the US Masters SwimmingChampionships. Regression analysis showed that in both men and womenendurance swimming performance (i.e., 1,500 m) declined linearly frompeak levels at age 35-40 yr until ~70 yr of age, whereuponperformance declined exponentially thereafter. In both genders, thevariability among the top 10 winning times in each 5-yr age intervalincreased markedly with advancing age. Compared with the 1,500-mfreestyle, performance in the 50-m freestyle (short-duration task)showed only a modest decline until ages 75 and 80 yr in women and men,respectively. The rate and magnitude of the declines in both short- andlong-duration swimming performance with age were significantly(P < 0.05) greater in women than in men. In the women, the percent decline in swimming performance over a50-yr age period from the 19- to 24-yr to the 69- to 74-yr age groupsbecame progressively greater from the shortest distance (50 m) to thetwo longest distances (800 and 1,500 m), whereas in men, no differenceswere observed in the magnitude of performance decline with age amongthe five longest distance events (i.e., 100-1,500 m). The percentgender difference in performance throughout the age range studiedbecame progressively smaller (P < 0.05) with increasing distance from 50 m (19 ± 1%) to 1,500 m (11 ± 1%). The findings in this cross-sectional study indicate that from peak levels at age 35-40 yr, physiological functionalcapacity, as assessed by swimming performance, decreases linearly until ~70-80 yr of age, whereupon the decline becomes exponential.Moreover, the rate of decline with advancing age appears to beassociated with event duration and gender.

     

Invited Review: Role of mechanophysiology in aging of ECM: effects of changes in mechanochemical transduction.

Mechanical forces play a role in the development and evolution of extracellular matrices (ECMs) found in connective tissue. Gravitational forces acting on mammalian tissues increase the net muscle forces required for movement of vertebrates. As body mass increases during development, musculoskeletal tissues and other ECMs are able to adapt their size to meet the increased mechanical requirements. However, the control mechanisms that allow for rapid growth in tissue size during development are altered during maturation and aging. The purpose of this mini-review is to examine the relationship between mechanical loading and cellular events that are associated with downregulation of mechanochemical transduction, which appears to contribute to aging of connective tissue. These changes result from decreases in growth factor and hormone levels, as well as decreased activation of the phosphorelay system that controls cell division, gene expression, and protein synthesis. Studies pertaining to the interactions among mechanical forces, growth factors, hormones, and their receptors will better define the relationship between mechanochemical transduction processes and cellular behavior in aging tissues.     

Acute effects of plyometric exercise on maximum squat performance in male athletes

This study examines the acute effects of plyometric exercise on 1 repetition maximum (RM) squat performance in trained male athletes. Twelve men (mean age +/- SD: 20.5 +/- 1.4 years) volunteered to participate in 3 testing sessions separated by at least 6 days of rest. During each testing session the 1RM was assessed on back squat exercise. Before all 3 trials subjects warmed up on a stationary cycle for 5 minutes and performed static stretching. Subjects then performed 5 submaximal sets of 1-8 repetitions before attempting a 1RM lift. Subjects rested for at least 4 minutes between 1RM trials. During the first testing session (T1) subjects performed a series of sets with increasing load until their 1RM was determined. During the second and third testing sessions subjects performed in counterbalanced order either 3 double-leg tuck jumps (TJ) or 2 depth jumps (DJ) 30 seconds before each 1RM attempt. The average 1RM lifts after T1 and testing sessions with TJ or DJ were 139.6 +/- 29.3 kg, 140.5 +/- 25.6 kg, and 144.5 +/- 30.2 kg, respectively (T1 < DJ; p < 0.05). These data suggest that DJ performed before 1RM testing may enhance squat performance in trained male athletes.     

Declines in physiological functional capacity with age: a longitudinal study in peak swimming performance.

We followed up swimming performance times of 321 women and 319 men who participated in the US Masters Swimming Championships over a 12-yr period. All swimmers placed in the top 10 in their age group over 3 yr (mean = 5 yr). A random coefficients model for repeated measures was used to derive a line of best fit from a group of regression lines for each subject. Both 50- and 1,500-m swimming performance declined modestly until approximately 70 yr of age, where a more rapid decline was observed in both men and women. Compared with 1,500-m swimming, the 50-m freestyle declined more modestly and slowly with age. The rate and magnitude of declines in swimming performance with age were greater in women than in men in 50-m freestyle; such sex-related differences were not observed in 1,500-m freestyle. Overall, the variability along a population regression line increased markedly with advancing age. The present longitudinal findings indicate that 1) swimming performance declines progressively until age 70, where the decrease becomes quadratic; 2) the rates of the decline in swimming performance with age are greater in a long-duration than in a short-duration event, suggesting a relatively smaller loss of anaerobic muscular power with age compared with cardiovascular endurance; 3) the age-related rates of decline are greater in women than in men only in a short-duration event; and 4) the variability of the age-related decline in performance increases markedly with advancing age.     

Special feature for the Olympics: effects of exercise on the immune system: overtraining effects on immunity and performance in athletes

Overtraining is a process of excessive exercise training in high-performance athletes that may lead to overtraining syndrome. Overtraining syndrome is a neuroendocrine disorder characterized by poor performance in competition, inability to maintain training loads, persistent fatigue, reduced catecholamine excretion, frequent illness, disturbed sleep and alterations in mood state. Although high-performance athletes are generally not clinically immune deficient, there is evidence that several immune parameters are suppressed during prolonged periods of intense exercise training. These include decreases in neutrophil function, serum and salivary immunoglobulin concentrations and natural killer cell number and possibly cytotoxic activity in peripheral blood. Moreover, the incidence of symptoms of upper respiratory tract infection increases during periods of endurance training. However, all of these changes appear to result from prolonged periods of intense exercise training, rather than from the effects of overtraining syndrome itself. At present, there is no single objective marker to identify overtraining syndrome. It is best identified by a combination of markers, such as decreases in urinary norepinephrine output, maximal heart rate and blood lactate levels, impaired sport performance and work output at 110% of individual anaerobic threshold, and daily self-analysis by the athlete (e.g. high fatigue and stress ratings). The mechanisms underlying overtraining syndrome have not been clearly identified, but are likely to involve autonomic dysfunction and possibly increased cytokine production resulting from the physical stress of intense daily training with inadequate recovery.     

Protein synthesis and antioxidant capacity in aging mice: effects of long-term voluntary exercise

Exercise increases metabolic rate and the production of reactive oxygen species (ROS) but also elevates protein turnover. ROS cause damage to macromolecules (e.g., proteins) and thereby contribute to aging. Protein turnover removes and replaces damaged proteins. The balance between these two responses may underlie beneficial effects of physical activity on aging. Effects of lifelong exercise on antioxidant enzyme activities and fractional synthesis rate of protein (FSRP) were examined at various ages (2-26 mo) in heart, liver, and muscle of mice that had been selectively bred for high wheel-running activity, housed with (S+) or without (S-) a running wheel, and their random-bred controls (C+) housed with running wheels. FSRP decreased with age and increased in muscle of young, but not old, activity-selected mice. Enzyme activity of superoxide dismutase and glutathione peroxidase decreased with age and showed a peak at 10 mo of age in liver. Selection for wheel-running activity did not affect antioxidant enzyme activity. Daily energy expenditure correlated positively with antioxidant levels in liver. This might indicate that oxidative stress (ROS production) increases with metabolic rate, driving upregulation of antioxidant enzymes. Alternatively, the elevated energy expenditure may reflect the energetic cost of elevated protection, consistent with the disposable-soma hypothesis and with other studies showing positive links between energy expenditure and life span. Long-term elevations in voluntary exercise did not result in elevations in antioxidant enzyme activities or protein synthesis rates.     

Morphology,performance, fitness: functional insight into a post-Pleistocene radiation of mosquitofish

Bahamas mosquitofish (Gambusia hubbsi) colonized blue holes during the past approximately 15 000 years and exhibit relatively larger caudal regions in blue holes that contain piscivorous fish. It is hypothesized that larger caudal regions enhance fast-start escape performance and thus reflect an adaptation for avoiding predation. Here I test this hypothesis using a three-pronged, experimental approach. First, G. hubbsi from blue holes with predators were found to possess both greater fast-start performance and greater survivorship in the presence of predatory fish. Second, using individual-level data to investigate the morphology–performance–fitness pathway, I found that (i) fish with larger caudal regions produced higher fast-start performance and (ii) fish with higher fast-start performance enjoyed greater survivorship in the presence of fish predators—trends consistently observed across both predator regimes. Finally, I found that morphological divergence between predator regimes at least partially reflects genetic differentiation, as differences were retained in fish raised in a common laboratory environment. These results suggest that natural selection favours increased fast-start performance in the presence of piscivorous fish, consequently driving the evolution of larger caudal regions. Combined with previous work, this provides functional insight into body shape divergence and ecological speciation among Bahamian blue holes.     

Mechanistic insight into the physiological relevance of helical blood flow in the human aorta: an in vivo study

The hemodynamics within the aorta of five healthy humans were investigated to gain insight into the complex helical flow patterns that arise from the existence of asymmetries in the aortic region. The adopted approach is aimed at (1) overcoming the relative paucity of quantitative data regarding helical blood flow dynamics in the human aorta and (2) identifying common characteristics in physiological aortic flow topology, in terms of its helical content. Four-dimensional phase-contrast magnetic resonance imaging (4D PC MRI) was combined with algorithms for the calculation of advanced fluid dynamics in this study. These algorithms allowed us to obtain a 4D representation of intra-aortic flow fields and to quantify the aortic helical flow. For our purposes, helicity was used as a measure of the alignment of the velocity and the vorticity. There were two key findings of our study: (1) intra-individual analysis revealed a statistically significant difference in the helical content at different phases of systole and (2) group analysis suggested that aortic helical blood flow dynamics is an emerging behavior that is common to normal individuals. Our results also suggest that helical flow might be caused by natural optimization of fluid transport processes in the cardiovascular system, aimed at obtaining efficient perfusion. The approach here applied to assess in vivo helical blood flow could be the starting point to elucidate the role played by helicity in the generation and decay of rotating flows in the thoracic aorta.     

Special feature for the Olympics: effects of exercise on the immune system: infections and exercise in high-performance athletes

The elite athlete has a potentially increased sensitivity to respiratory infections, rendering protective measures particularly important. Some other infections that may appear in clusters in the sports setting, such as gastroenteritis, leptospirosis, herpes simplex and viral hepatitis, also require special precautionary attention. Strenuous exercise during ongoing infection and fever may be hazardous and should always be avoided. In addition, early symptoms of infection warrant caution until the nature and severity of the infection become apparent. Because myocarditis may or may not be accompanied by fever, malaise or catarrhal symptoms, athletes should be informed about the symptoms suggestive of this disease. Although sudden unexpected death resulting from myocarditis is rare, exercise should be avoided whenever myocarditis is suspected. Guidelines are suggested for the management and counselling of athletes suffering from infections, including recommendations on when to resume training. Acute febrile infections are associated with decreased performance resulting from muscle wasting, circulatory deregulation and impaired motor coordination, which require variable amounts of time to become normalized once the infection is over.     

Effectiveness of taping on functional performance in elite athletes: A systematic review

Taping has been showing its effect on the rehabilitation aspect with numerous reviews. However, there is lack of evidence on the effect of taping on functional performance, espectially in elite sports settings. This review aimed to evaluate the effectiveness of taping intervention on sports-related functional performance among the elite athlete population. Online databases such as Ovid MEDLINE, ProQuest, PubMed, ScienceDirect, Scopus, SPORTDiscus, and Web of Science were searched. Eligibility criteria were listed as follows: (i) English, (ii) academic journal, (iii) research article, (iv) elite or professional athletes, (v) experimental research design, (vi) sport, (vii) taping, and (viii) functional performance. Specific emphases were targeted on within-subject comparison and healthy subjects. The PEDro scale was utilized for appraising on the statistical information, as well as internal and external validity. The Cohen's d effect size with 95 percent confidence intervals was used to compare taped versus not-taped condition. Nine studies were included in this review and 25 comparisons were extracted. Positive effects were found on balance performance with rigid tape, and horizontal jump performance with elastic tape. Alternatively, negative effects were found on vertical jump performance. An interesting finding was noted on the effect of taping applied after 24 h. Overall, taping could be a beneficial practice for elite sports performance.     

Invited review: Effects of acute exercise and exercise training on insulin resistance.

Insulin resistance of skeletal muscle glucose transport is a key defect in the development of impaired glucose tolerance and Type 2 diabetes. It is well established that both an acute bout of exercise and chronic endurance exercise training can have beneficial effects on insulin action in insulin-resistant states. This review summarizes the present state of knowledge regarding these effects in the obese Zucker rat, a widely used rodent model of obesity-associated insulin resistance, and in insulin-resistant humans with impaired glucose tolerance or Type 2 diabetes. A single bout of prolonged aerobic exercise (30-60 min at approximately 60-70% of maximal oxygen consumption) can significantly lower plasma glucose levels, owing to normal contraction-induced stimulation of GLUT-4 glucose transporter translocation and glucose transport activity in insulin-resistant skeletal muscle. However, little is currently known about the effects of acute exercise on muscle insulin signaling in the postexercise state in insulin-resistant individuals. A well-established adaptive response to exercise training in conditions of insulin resistance is improved glucose tolerance and enhanced skeletal muscle insulin sensitivity of glucose transport. This training-induced enhancement of insulin action is associated with upregulation of specific components of the glucose transport system in insulin-resistant muscle and includes increased protein expression of GLUT-4 and insulin receptor substrate-1. It is clear that further investigations are needed to further elucidate the specific molecular mechanisms underlying the beneficial effects of acute exercise and exercise training on the glucose transport system in insulin-resistant mammalian skeletal muscle.     

Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men.

To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (VO(2 peak)) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in VO(2 peak) correlated positively with the initial values (r = 0.73, P < 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60% VO(2 peak) (P < 0.001); they also had an earlier increase in [NE], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.     

The effects of progressive exercise on cardiovascular function in elite athletes: focus on oxidative stress

Some side-effects of excessive physical training are ascribed to reactive oxygen species production. In this work we investigated the effects of progressively imposed maximal physical effort (levels I to V), using progressive maximal exercise test, on peripheral blood lactate, NO (through NO2-), superoxide anion (O2-) and methemoglobin (MetHb) in a group of 19 elite soccer players. Blood lactate (mmol/L) was increased (4.55, level V vs. resting level, 1.95). The basal production of NO2- was in the direct relation with O2 consumption. Significant increase (p<0.05) in O2- values at effort level I (4.18) as compared to the resting value (4.01), and the significant increase (p<0.01 or p<0.05) in the MetHb (%) was found between II (18.79) and III (19.63) or between II and IV (19.24) effort levels, respectively. The regression lines of NO2- and O2- crossed at the level of the respiratory compensation point (RC), suggesting that RC could be of a crucial importance not only in the anaerobic and aerobic metabolism but in mechanisms of signal transductions as well. The results could be of the theoretical interest and also useful in designing an athlete training strategy.     

Acute effects of verbal feedback on upper-body performance in elite athletes

Argus, CK, Gill, ND, Keogh, JWL, and Hopkins, WG. Acute effects of verbal feedback on upper-body performance in elite athletes. J Strength Cond Res 25(12): 3282-3287, 2011-Improved training quality has the potential to enhance training adaptations. Previous research suggests that receiving feedback improves single-effort maximal strength and power tasks, but whether quality of a training session with repeated efforts can be improved remains unclear. The purpose of this investigation was to determine the effects of verbal feedback on upper-body performance in a resistance training session consisting of multiple sets and repetitions in well-trained athletes. Nine elite rugby union athletes were assessed using the bench throw exercise on 4 separate occasions each separated by 7 days. Each athlete completed 2 sessions consisting of 3 sets of 4 repetitions of the bench throw with feedback provided after each repetition and 2 identical sessions where no feedback was provided after each repetition. When feedback was received, there was a small increase of 1.8% (90% confidence limits, ±2.7%) and 1.3% (±0.7%) in mean peak power and velocity when averaged over the 3 sets. When individual sets were compared, there was a tendency toward the improvements in mean peak power being greater in the second and third sets. These results indicate that providing verbal feedback produced acute improvements in upper-body power output of well-trained athletes. The benefits of feedback may be greatest in the latter sets of training and could improve training quality and result in greater long-term adaptation.     

Invited review: effect of acute exercise on insulin signaling and action in humans.

After a single bout of exercise, insulin action is increased in the muscles that were active during exercise. The increased insulin action has been shown to involve glucose transport, glycogen synthesis, and glycogen synthase (GS) activation as well as amino acid transport. A major mechanism involved in increased insulin stimulation of glucose uptake after exercise seems to be the exercise-associated decrease in muscle glycogen content. Muscle glycogen content also plays a pivotal role for the activity of GS and for the ability of insulin to increase GS activity. Insulin signaling in human skeletal muscle is activated by physiological insulin concentrations, but the increase in insulin action after exercise does not seem to be related to increased insulin signaling [insulin receptor tyrosine kinase activity, insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation (RS1), IRS-1-associated phosphatidylinositol 3-kinase activity, Akt phosphorylation (Ser(473)), glycogen synthase kinase 3 (GSK3) phosphorylation (Ser(21)), and GSK3alpha activity], as measured in muscle lysates. Furthermore, insulin signaling is also largely unaffected by exercise itself. This, however, does not preclude that exercise influences insulin signaling through changes in the spatial arrangement of the signaling compounds or by affecting unidentified signaling intermediates. Finally, 5'-AMP-activated protein kinase has recently entered the stage as a promising player in explaining at least a part of the mechanism by which exercise enhances insulin action.     

Invited Review: Role of insulin in translational control of protein synthesis in skeletal muscle by amino acids or exercise.

Protein synthesis in skeletal muscle is modulated in response to a variety of stimuli. Two stimuli receiving a great deal of recent attention are increased amino acid availability and exercise. Both of these effectors stimulate protein synthesis in part through activation of translation initiation. However, the full response of translation initiation and protein synthesis to either effector is not observed in the absence of a minimal concentration of insulin. The combination of insulin and either increased amino acid availability or endurance exercise stimulates translation initiation and protein synthesis in part through activation of the ribosomal protein S6 protein kinase S6K1 as well as through enhanced association of eukaryotic initiation factor eIF4G with eIF4E, an event that promotes binding of mRNA to the ribosome. In contrast, insulin in combination with resistance exercise stimulates translation initiation and protein synthesis through enhanced activity of a guanine nucleotide exchange protein referred to as eIF2B. In both cases, the amount of insulin required for the effects is low, and a concentration of the hormone that approximates that observed in fasting animals is sufficient for maximal stimulation. This review summarizes the results of a number of recent studies that have helped to establish our present understanding of the interactions of insulin, amino acids, and exercise in the regulation of protein synthesis in skeletal muscle.