Binh Quach

The effect of inspiratory muscle training on high-intensity, intermittent running performance to exhaustion.

The effects of inspiratory muscle (IM) training on maximal 20 m shuttle run performance (Ex) during Yo-Yo intermittent recovery test and on the physiological and perceptual responses to the running test were examined. Thirty men were randomly allocated to 1 of 3 groups. The experimental group underwent a 6 week pressure threshold IM training program by performing 30 inspiratory efforts twice daily, 6 d/week, against a load equivalent to 50% maximal static inspiratory pressure. The placebo group performed the same training procedure but with a minimal inspiratory load. The control group received no training. In post-intervention assessments, IM function was enhanced by >30% in the experimental group. The Ex was improved by 16.3% +/- 3.9%, while the rate of increase in intensity of breathlessness (RPB/4i) was reduced by 11.0% +/- 6.2%. Further, the whole-body metabolic stress reflected by the accumulations of plasma ammonia, uric acid, and blood lactate during the Yo-Yo test at the same absolute intensity was attenuated. For the control and placebo groups, no significant change in these variables was observed. In comparison with previous observations that the reduced RPB/4i resulting from IM warm-up was the major reason for improved Ex, the reduced RPB/4i resulting from the IM training program was lower despite the greater enhancement of IM function, whereas improvement in Ex was similar. Such findings suggest that although both IM training and warm-up improve the tolerance of intense intermittent exercise, the underlying mechanisms may be different.

Specific inspiratory muscle warm-up enhances badminton footwork performance

The effects of inspiratory muscle (IM) warm-up on IM function and on the maximum distance covered in a subsequent incremental badminton-footwork test (FWmax) were examined. Ten male badminton players were recruited to perform identical tests in three different trials in a random order. The control trial did not involve an IM warm-up, whereas the placebo and experimental trials did involve an IM warm-up consisting of two sets of 30-breath manoeuvres with an inspiratory pressure-threshold load equivalent to 15% (PLA) and 40% (IMW) maximum inspiratory mouth pressure, respectively. In the IMW trial, IM function was improved with 7.8%+/-4.0% and 6.9%+/-3.5% increases from control found in maximal inspiratory pressure at zero flow (P0) and maximal rate of P0 development (MRPD), respectively (p<0.05). FWmax was enhanced 6.8%+/-3.7%, whereas the slope of the linear relationship of the increase in the rating of perceived breathlessness for every minute (RPB/min) was reduced (p<0.05). Reduction in blood lactate ([La-]b) accumulation was observed when the test duration was identical to that of the control trial (P<0.05). In the PLA trial, no parameter was changed from control. For the changes (Delta) in parameters in IMW (n=10), negative correlations were found between DeltaP0 and DeltaRPB/min (r2=0.58), DeltaMRPD and DeltaRPB/min (r2=0.48), DeltaRPB/min, and DeltaFWmax (r2=0.55), but not between Delta[La-]b accumulation and DeltaFWmax. Such findings suggest that the IM-specific warm-up improved footwork performance in the subsequent maximum incremental badminton-footwork test. The improved footwork was partly attributable to the reduced breathless sensation resulting from the enhanced IM function, whereas the contribution of the concomitant reduction in [La-]b accumulation was relatively minor.

Reduced sensations of intensity of breathlessness enhances maintenance of intense intermittent exercise

To identify the effect of normal breathlessness sensation elicited during intense intermittent exercise at exhaustion on limitation of exercise maintenance (Ex), the contribution of the flow-resistive unloading effect of normoxic helium–oxygen breathing on the breathlessness sensation to the change in the Ex was examined. Seven men repeatedly performed 12-s exercise at 160% maximal aerobic power output followed by passive recovery for 18-s under normal (CON) and unloaded (UL) breathing conditions until exhaustion. In UL, Ex was enhanced [mean (SD) 127.2 (11.8)% CON] concomitantly with reduction in averaged peak inhaled mouth pressure (PPmi) of recorded breathing cycles that reflected approximate true inspiratory muscle force output. At the iso-time point of CON exhaustion, the reduction in PPmi to [75.7(10.2)% CON] in UL was concomitant with the reductions in the rating of perceived breathlessness (RPB) [87.5 (13.1)% CON] and in the slope of time course for RPB (RPB/2-min period) [82.1 (17.2)% CON]. It was also concomitant with increases in ventilation and total oxygen consumption. However, the augmented oxygen consumption did not result in lowering of subjects’ metabolic stress that was indicated by accumulations of blood lactate and plasma ammonia and uric acid. Nevertheless, the reductions in the RPB and RPB/2-min period, which reflected the breathlessness intensity, were correlated to the CON Ex enhancement in UL (RPB r=-0.57, RPB/2-min period r=-0.83; P<0.05). These findings implied that the normal noxious breathlessness sensation elicited during intense intermittent exercise at exhaustion might contribute to the limitation of subjects’ exercise maintenance.

CHRONIC AND ACUTE INSPIRATORY MUSCLE LOADING AUGMENT THE EFFECT OF A 6-WEEK INTERVAL PROGRAM ON TOLERANCE OF HIGH-INTENSITY INTERMITTENT BOUTS OF RUNNING

Tong, TK, Fu, FH, Eston, R, Chung, P-K, Quach, B, and Lu, K. Chronic and acute inspiratory muscle loading augment the effect of a 6-week interval program on tolerance of high-intensity intermittent bouts of running. J Strength Cond Res 24(11): 3041-3048, 2010-This study examined the hypothesis that chronic (training) and acute (warm-up) loaded ventilatory activities applied to the inspiratory muscles (IM) in an integrated manner would augment the training volume of an interval running program. This in turn would result in additional improvement in the maximum performance of the Yo-Yo intermittent recovery test in comparison with interval training alone. Eighteen male nonprofessional athletes were allocated to either an inspiratory muscle loading (IML) group or control group. Both groups participated in a 6-week interval running program consisting of 3-4 workouts (1-3 sets of various repetitions of selected distance [100-2,400 m] per workout) per week. For the IML group, 4-week IM training (30 inspiratory efforts at 50% maximal static inspiratory pressure [P0] per set, 2 sets·d−1, 6 d·wk−1) was applied before the interval program. Specific IM warm-up (2 sets of 30 inspiratory efforts at 40% P0) was performed before each workout of the program. For the control group, neither IML was applied. In comparison with the control group, the interval training volume as indicated by the repeatability of running bouts at high intensity was approximately 27% greater in the IML group. Greater increase in the maximum performance of the Yo-Yo test (control: 16.9 ± 5.5%; IML: 30.7 ± 4.7% baseline value) was also observed after training. The enhanced exercise performance was partly attributable to the greater reductions in the sensation of breathlessness and whole-body metabolic stress during the Yo-Yo test. These findings show that the combination of chronic and acute IML into a high-intensity interval running program is a beneficial training strategy for enhancing the tolerance to high-intensity intermittent bouts of running.

Functional fitness norms for community-dwelling older adults in Hong Kong

OBJECTIVE This study aimed to establish normative data for older adults in Hong Kong and explore age and sex differences in functional fitness. METHODS A sample of 944 independent community-dwellers, aged 65-74 years, was evaluated using the Senior Fitness Test battery in addition to hand grip and single leg stance tests. Normative data were reported for the 10th, 25th, 50th, 75th, and 90th percentiles in 5-year age groups. RESULTS Except for upper extremity muscle strength in women and body mass index (BMI) in both sexes, ageing-associated degradation was observed in all testing parameters especially in flexibility, balance, and agility. Significant sex differences were found in all testing parameters with the exception of BMI and static balance with eyes open. Moreover, men demonstrated higher capacities for muscle strength, agility, balance, and aerobic endurance, whereas women showed superior flexibility. CONCLUSION The normative values enable the evaluation of individual performance regarding the fitness status of older adults in Hong Kong.

A canonical correlation analysis on the relationship between functional fitness and health-related quality of life in older adults

OBJECTIVE This study aimed to explore the relationship between the functional fitness (FF) and health-related quality of life (HRQoL) in older adults, and to identify the key subdimensions of FF and HRQoL influencing their overall relationship. METHODS This cross-sectional study was performed among 851 independent community members (65-84 years; men=402). The Senior Fitness Test and the Short Form 36 Health Survey were used to measure FF and HRQoL, respectively. A canonical correlation analysis was conducted using seven fitness variables as predictors of eight HRQoL variables to examine the relationship between FF and HRQoL. RESULTS The overall FF was positively correlated with the overall HRQoL in both men (canonical correlation=0.350) and women (canonical correlation=0.456). The up-and-go and 2-min step contributed the most to FF, and physical functioning contributed the most to HRQOL among men. Conversely, the up-and-go and 30-s chair stand contributed the most to FF, and physical functioning contributed the most to HRQoL in women. CONCLUSIONS There were positive and moderate relationships between overall FF and overall HRQOL in older adults. The FF has a significant influence on HRQoL, particularly physical functioning. The main FF components influencing the relationship between FF and HRQoL in men are balance and agility and aerobic endurance, whereas in women they are balance and agility and lower extremity muscle strength. Results from this study facilitate comprehensively understanding the relationship between FF and HRQoL, and generating critical insight into HRQoL improvement from the perspective of FF enhancement.

Optimal workload of Wingate test: A comparison between normal and minor overfat young adults

We compared the optimal workload of Wingate test (WAnT), which was assigned according to total body mass (TBM), between two groups of eight young male adults. The leg anaerobic power and fat free mass of these two groups were comparable while their percent body fat was either within (NOR) or above normal range (OF). The optimal WAnT workload was derived individually from the polynomial regression of power-workload against of 75, 100, 110, 125 and 140 g.kg -1 TBM. It was found that the maximum power elicited from the various workloads in the WAnT was not differ- ent (P>0.05) between NOR and OF groups. Further, there was no difference in the optimal workload between the two groups (NOR: 120.7 ±13.6; OF: 114.0 ±7.2 g.kg -1 TBM, P>0.05). The findings suggest that the counting of fat mass in workload assignment in the WAnT may not affect the maximum power output in minor overfat adults.

A BRIEF NOTE ON THE VALIDITY AND RELIABILITY OF THE RATING OF PERCEIVED EXERTION SCALE IN MONITORING EXERCISE INTENSITY AMONG CHINESE OLDER ADULTS IN HONG KONG.

This study examined the validity and reliability of the Cantonese Borg 6–20 Rating of Perceived Exertion (RPE) scale in monitoring exercise intensity among Chinese older adults. A total of 40 apparently healthy older adults (16 men, 24 women; M age = 69.8yr., SD = 4.56) performed two trials of three intermittent exercise tests administered in random order using the cycle ergometer. Results revealed significant differences of RPE, HR, and VO2 between different workloads, and there were moderate to high correlations between RPE and HR and VO2, respectively. Results also found moderate consistency of RPE between Trial 1 and Trial 2. These indicated that the Cantonese 6–20 RPE scale can be used as a valid and reliable tool for monitoring exercise intensity among the Chinese older adults.