Differences in autonomic modulation of heart rate during arm and leg exercise.

Heart rate (HR) is higher during dynamic arm exercise than during leg exercise at equal oxygen consumption levels, but the physiological background for this difference is not completely understood. The vagally mediated beat-to-beat R-R interval fluctuation decreases until the level of approximately 50% of maximal oxygen consumption during an incremental bicycle exercise, but the vagal responses to arm exercise are not well known. Changes in autonomic modulation of HR were compared during arm and leg exercise by measuring beat-to-beat R-R interval variability from a Poincaré plot normalized for the average R-R interval (SD1n), a measure of vagal activity, in 14 healthy male subjects (age 20 +/- 4 years) who performed graded bicycle and arm cranking tests until exhaustion. Seven of the subjects also performed the dynamic arm and leg tests after beta-adrenergic blockade (propranolol 0.2 mg kg-1 i.v.). More rapid reduction occurred in SD1n during the low-intensity level of dynamic arm exercise than during dynamic leg exercise without beta-blockade (e.g. 11 +/- 6 vs. 20 +/- 10 at the oxygen consumption level of 1.2 l min-1; P < 0.001) and with beta-blockade (e.g. 13 +/- 4 vs. 25 +/- 10 at the level of 1.0 l min-1; P < 0.05), and the mean HR was significantly higher during submaximal arm work than during leg work in both cases (e.g. during beta-blockade 81 +/- 12 vs. 74 +/- 6 beats min-1 at the level of 1.0 l min-1; P < 0.05). These data show that dynamic arm exercise results in more rapid withdrawal of vagal outflow than dynamic leg exercise.

Vagal modulation of heart rate during exercise: effects of age and physical fitness.

This study was designed to assess the effects of age and physical fitness on vagal modulation of heart rate (HR) during exercise by analyzing the instantaneous R-R interval variability from Poincaré plots (SD1) at rest and at different phases of a bicycle exercise test in a population of healthy males. SD1 normalized for the average R-R interval (SD1n), a measure of vagal activity, was compared at rest and during exercise among subjects of ages 24-34 (young, n = 25), 35-46 (middle-aged, n = 30), and 47-64 yr (old, n = 25) matched for peak O2 consumption (VO2 peak) and among subjects with VO2 peak of 28-37 (poor, n = 25), 38-45 (average, n = 36), and 46-60 ml.kg-1.min-1 (good, n = 25) matched for age. SD1n was higher at rest in the young subjects than in the middle-aged or old subjects (39 +/- 14, 27 +/- 16, and 21 +/- 8, respectively; P < 0.001), but the age-related differences in SD1n were smaller during exercise [e.g., 11 +/- 5, 9 +/- 5, and 8 +/- 4 at the level of 100 W; P = not significant (NS)]. The age-matched subjects with good, average, and poor VO2 peak showed no difference in SD1n at rest (32 +/- 17, 28 +/- 13, and 26 +/- 11, respectively; P = NS), but SD1n differed significantly among the groups from a low to a moderate exercise intensity level (e.g., 13 +/- 6, 10 +/- 5, and 6 +/- 3 for good, average, and poor fitness groups, respectively; P < 0.001, 100 W). These data show that poor physical fitness is associated with an impairment of cardiac vagal function during exercise, whereas aging itself results in more evident impairment of vagal function at rest.

Safety and feasibility of a health-related fitness test battery for adults.

BACKGROUND AND PURPOSE: Health-related fitness (HRFI) assessment may be useful in promoting physical activity. Health-related fitness refers to those components of fitness that are related to health status. The safety and feasibility of a test battery designed for the assessment of HRFI were evaluated. SUBJECTS AND METHODS: Middle-aged men (n = 246) and women (n = 254), evenly selected from five age cohorts of a random sample (N = 826), were tested. The subjects had a mean age of 47.0 years (SD = 7.9, range = 37-57). Screening to identify subjects with health limitations was conducted by fitness testers who had master's degrees in sport or health sciences. Safety was assessed in terms of acute complications, delayed-onset muscle soreness (DOMS), and heart rate after each test. Subject exclusion and time costs were evaluated for feasibility. RESULTS: No acute complications occurred. The leg function test caused severe DOMS among inactive women. The overall exclusion rate increased with age. Up to 27% of subjects aged 52 and 57 years were excluded from muscle endurance tests, mainly due to self-reported heart disease or elevated blood pressures. Over 90% of the subjects, however, qualified for balance, flexibility, muscle force, and walk tests. CONCLUSION AND DISCUSSION: The test battery offers a safe and feasible method for the assessment of HRFI in working-aged adults, with the limitation that the one-leg squat function test may cause DOMS, particularly in inactive women.

Health-related fitness test battery for adults: aspects of reliability.

OBJECTIVE: In two studies, the reliability of 3 balance, 2 flexibility, and 4 muscular strength tests proposed as test items were investigated in a health-related fitness (HRF) test battery for adults. DESIGN: Methodological study. SETTING: A health promotion research institute. SUBJECTS: In study A, volunteers (n=42) from two worksites participated. In study B, a population sample (n=510) of 37-to 57-year-old men and women was selected. MAIN OUTCOME MEASURES: Intraclass correlation coefficient of repeated measures was used to assess inter-rater reliability. The degree of measurement error was expressed as the standard error of measurement. The mean difference with 95% confidence intervals between the testing days or test trials was used to assess test-retest or trial-to-trial reproducibility. The coefficient of variation(CV=[SD/mean] x 100%) from day to day was also calculated. RESULTS: The following tests appeared to provide acceptable reliability as methods for field assessment of HRF: standing on one leg with eyes open for balance, side-bending of the trunk for spinal flexibility, modified push-ups for upper body muscular function, and jump and reach and one leg squat for leg muscular function. CONCLUSIONS: This reliability assessment provided useful information on the characteristics of potential test items in a HRF test battery for adults and on the limitations of its practical use. Testers must be properly trained to ensure reliable assessment of HRF of adults.