Diaphragm Function in Elite Weightlifters With and Without Chronic Low Back Pain and its Impacts on Sports Performance.

Abstract: Zhou, EFM, Wong, AYL, Peng, J, Lin, G, Wen, T, Fang, J, Zhou, C, and Fu, SN. Diaphragm function in elite weightlifters with and without chronic low back pain and its impacts on sports performance. J Strength Cond Res XX(X): 000-000, 2024-The aim of this study was to compare diaphragm function between elite weightlifters with and without chronic low back pain (LBP) and to explore the associations between diaphragm function and sports performance. Forty-nine elite weightlifters aged 16-26 years were recruited, including 29 women (16-25 years, mean ± SD = 19.93 ± 2.70 years) and 20 men (16-26 years, mean ± SD = 20.95 ± 2.68 years). Of these, 23 subjects had chronic LBP. Diaphragm thickness and excursion were assessed using ultrasonography, and maximal inspiratory pressure (MIP), measured with POWERbreathe KH2, served as indicators of diaphragm contractility and strength, respectively. Sports performance was gauged through maximal snatch and clean and jerk lifts. Group differences and performance correlations were analyzed with consideration for confounders. The significance was set at p ≤ 0.05. Weightlifters with chronic LBP demonstrated significantly lower diaphragmatic contractility: diaphragm thickening fraction (by 21%; mean difference [MD] = 0.09, p = 0.04, Cohen's d = 0.69) and diaphragm excursion (by 18%; MD = 0.99, p < 0.01, Cohen's d = 0.89) compared with non-LBP controls. In addition, MIP was positively related to snatch (r = 0.34, p = 0.02) and clean and jerk (r = 0.43, p < 0.01) lifts. This study revealed that elite weightlifters with chronic LBP exhibit reduced diaphragm contractility, and inspiratory muscle force output (primary diaphragm) was associated with lifting performance. Incorporating diaphragm strengthening into training and rehabilitation might enhance performance and aid in LBP management, offering a dual benefit for athletes.