Aerobic capacity and isometric knee flexion strength fatigability are related to knee kinesthesia in physically active women

BACKGROUND: Fatiguing exercise may impair functional joint stability and increase injury risk. Musculoskeletal and physiological characteristics are related to fatigue, but their relationship with proprioceptive changes following fatigue is unknown. OBJECTIVE: To establish the relationship between strength and physiological characteristics and changes in knee proprioception following fatigue. METHODS: Physically active women (N = 20, 28.7 +/- 5.6 years, 165.6 +/- 4.3 cm, 61.8 +/- 8.0 kg) underwent isokinetic knee strength and peak oxygen uptake (VO2peak)/lactate threshold (LT) testing during Visit 1, and threshold to detect passive motion (TTDPM) and isometric knee strength testing before and after fatiguing exercise during Visit 2. RESULTS: Fatigue demonstrated no effect on TTDPMdespite a decrease in isometric knee flexion strength (P < 0.05). Strength and physiological variables were not significantly correlated with changes in TTDPM. VO2peak was correlated with pre-fatigue (r = -0.50) and post-fatigue (r = -0.52) TTDPM into extension (P < 0.05), and further analyses demonstrated that post-fatigue changes in isometric knee flexion strength and strength ratio were related to post-fatigue changes in proprioception (r = -0.62 and -0.40, P < 0.05). CONCLUSIONS: Physically active women with higher aerobic capacity exhibit enhanced knee proprioception, and may benefit from training to strengthen and reduce the fatigability of the knee flexors following intense exercise, as these changes were associated with reduced proprioception.