Smoking Impact on Grip Strength and Fatigue Resistance: Implications for Exercise and Hand Therapy Practice

Abstract

Grip strength assessment reflects on overall health of the musculoskeletal system and is a predictor of functional prognosis and mortality. The purpose of this study was: examine whether grip-strength and fatigue resistance are impaired in smokers, determine if smoking-related impairments (fatigue-index) can be predicted by demographic data, duration of smoking, packets smoked-per-day, and physical activity. Maximum isometric grip strength (MIGS) of male smokers (n = 111) and nonsmokers (n = 66) was measured before/after induced fatigue using Jamar dynamometer at 5-handle positions. Fatigue index was calculated based on percentage change in MIGS initially and after induced fatigue. Number of repetitions to squeeze the soft rubber ball to induce fatigue was significantly lower in smokers compared with nonsmokers (t = 10.6, P < .001 dominant hand; t = 13.9, P < .001 nondominant), demonstrating a significantly higher fatigue-index for smokers than nonsmokers (t = -8.7, P < .001 dominant hand; t = -6.0, P < .001 nondominant). The effect of smoking status on MIGS scores was significantly different between smokers and nonsmokers after induced fatigue (β = -3.98, standard error = 0.59, P < .001) where smokers experienced on average a reduction of nearly 4 MIGS less than nonsmokers before fatigue. Smoking status was the strongest significant independent predictor of the fatigue-index. Smokers demonstrated reduced grip strength and fast fatigability in comparison with nonsmokers.