EFFECTS OF SIX WEEKS INSPIRATORY MUSCLE STRENGTH TRAINING ON HANDGRIP STRENGTH IN HEALTHY YOUNG ADULTS

Abstract

Previous work has shown that 5 minutes of inspiratory muscle strength training (IMST), 5 days/week increases respiratory muscle strength after 6 weeks. Respiratory muscle strength has been shown to correlate with handgrip strength, which has been found to be at least a moderate indicator of overall strength, or functional capacity. Here, we explore the effects of IMST on functional capacity via the assessment of handgrip strength in recreationally active men and women. Seven (5 male and 2 female) subjects undertook a 6-week intervention comprising 30 inspiratory efforts against a resistance each day, 5 days/week. Pre-and post-training measures included maximal inspiratory pressure (PImax, mmHg), maximal handgrip force (Newtons; N), respiratory endurance (sec) and handgrip endurance (sec). Male and female subjects showed increases in respiratory muscle strength (P < 0.001) and respiratory endurance (P= 0.01) at Week 6 compared to Week 1. Consistent with previously published literature,we saw no change in maximal handgrip strength (P = 0.29) post IMST. However, contrary to expectation, we noted declines in handgrip endurance at Week6 vs.Week 1 in the majority (5/7) of subjects. On the basis of these outcomes in a small cohort of healthy young adults, we conclude that 6 weeks IMST confers significant benefits for respiratory strength and endurancebut does not impact functional capacity as measured by handgrip function. The declines in grip endurance noted post IMST are attributed to within subject (i.e., pre vs. post) differences in execution of the grip endurance task. Measures that conserve subjects’ elbow, wrist and hand position across test-retest endurance trials and the incorporation of additional surface EMG recording locations may help to reduce such variability in subsequent studies.