Influence of age and physical training on measures of cardiorespiratory and muscle endurance.

This study describes associations between age, physical training and measures of muscle and cardiorespiratory endurance. The subjects were 5079 healthy male soldiers aged 18-53 years from 14 Army installations in the United States. The subjects completed as many push-ups as possible in 2 min, as many sit-ups as possible in 2 min, and performed a timed 3.2-km run. The training level was assessed by asking the subjects two questions about the frequency (times each week) and duration (hours each week) of their physical training. For all three performance events there were significant declines with age, but at a given age, groups that trained more demonstrated higher performance levels than groups that trained less. For the 3.2-km run, the age-associated rate of performance decline was less in the groups that trained more, and greater amounts of training resulted in progressively less performance decline with age. For push-ups and sit-ups, the training level did not systematically influence the age-related rate of performance decline. The results suggest that tasks involving different physiological systems may be influenced differentially by age and training. Training may slow age-associated performance declines in tasks requiring cardiorespiratory endurance but not in tasks requiring muscle endurance.

Effects of varying doses of smokeless tobacco at rest and during brief, high-intensity exercise.

To determine the influence of varying doses of smokeless tobacco (moist snuff) on resting heart rate and blood pressure and the performance of brief, high-intensity exercise, 12 snuff users were examined at rest and while performing Wingate Anaerobic Tests after taking six different doses of snuff. Snuff caused an increase in heart rate; the larger the dose, the larger the response. Increases in systolic and diastolic blood pressure also occurred but were similar at all doses. Performance of brief, high-intensity exercise was unaffected, so that there was no benefit for such activities (e.g., sprinting bases in base ball).

1988 active Army physical fitness survey.

The U.S. Army Physical Fitness School (USAPFS) at Ft. Benjamin Harrison, IN was tasked with measuring the physical fitness of the active Army. Performance on the Army Physical Fitness Test (APFT) was used to determine fitness levels. Data were collected at 14 U.S. Army installations CONUS-wide between October 1 and November 30, 1988. Five thousand three hundred forty-six male and 676 female active Army soldiers (N = 6.022) between the ages of 17-52 and in 60 military occupational specialties (MOSs) participated in the study. Generally, the results were favorable. Senior age groups performed well overall, especially females. Improvement in muscular strength and endurance conditioning since 1984 was also observed. However, concern was raised about poor performance in the youngest age group (17-21), where 16.6% of the males failed the 2-mile run event and 29.0% failed overall. Likewise, for females in the 17-21 year age group, 28.8% failed the 2-mile run and 36.0% failed overall. Several reasons are suggested for the poor performance of the younger age groups, including inadequate leadership in fitness training and low levels of self-motivation. This study suggest that many soldiers, especially young soldiers, may not possess sufficient levels of physical fitness to meet the physical demands of war.

Blood chemistry of current and previous anabolic steroid users.

While the use of anabolic-androgenic steroids appears to be increasing, little is known about the long-term effects of these drugs. This study compared selected blood profiles of current and former steroid-using athletes to expected values for non-drug-using populations. The results are consistent with previous research findings that steroids can have acute negative effects on liver function, lipoprotein fractions, and testosterone production. The results suggest that side effects vary widely among individuals and are drug and dose dependent. Normal function appears to return after drug use is discontinued. These data emphasize the difficulty physicians have interpreting clinical tests when dealing with those who use or have used anabolic steroids. Clearly more research is needed regarding the effects of these drugs.

Longitudinal assessment of responses by triathletes to swimming, cycling, and running.

Fourteen triathletes (eight male, six female) were tested four times (in February, May, August, and October) to monitor adaptations to training for a triathlon (1.9-km swim, 90.3-km bike, 21.1-km run). VO2max was measured during treadmill running (TR), cycle ergometry (CE), and tethered swimming (TS). Lactate threshold (LT), defined as the VO2 at a lactate concentration of 4 mM, was determined during TR and CE. In all sessions, TS VO2max was less than TR and CE (P less than 0.05), and CE was less than TR (P less than 0.05). Means for Session I were 57.4, 53.4, and 48.3 ml.min-1.kg-1 for TR, CE, and TS, respectively. Corresponding values for Session IV were 58.4, 56.0, and 47.8 ml.min-1.kg-1. The only significant increase in VO2max was for CE (5%). VO2 at the LT increased from Session I to IV for both TR (6%) and CE (10%); the LT for TR was at a higher VO2 than for CE in all sessions. The percent VO2max at LT for TR in Sessions I and IV was 80 and 85%, respectively. Analogous values for CE were 72 and 76%. The minimal increases in VO2max suggest that subjects had reached their potential in this parameter. Improvements in race performance were probably attained through peripheral adaptations, as suggested by increases in the VO2 at LT. The occurrence of the LT at a lower percent VO2max in cycling than in running suggests that the triathletes had greater potential for improvement in cycling.