Changes In Peak Torque Following Different Exercise Modalities To Fatigue

Exercise modalities come in all different types with eccentric training believed to cause the most muscle damage. As far as a which type of modality causes the most acute fatigue is still undetermined. PURPOSE: To determine what modality of exercise (isometric, isotonic, eccentric isokinetic) elicits the greatest fatigue. METHODS: Forty participants which included 20 females (20.5 ± 1.2 years, 162.1 ± 3.1 cm, 60.3 ± 9.3 kg) and 20 males (21.1 ± 0.9 years, 178.8 ± 9.5 cm, 82.6 ± 18.9 kg) volunteered for the study and were all free of knee pain or injury. Participants visited the lab on 4 different occasions and performed unilateral knee extensions with different modalities on each day on an isokinetic dynamometer. The modalities consisted of: isokinetic at a speed of 60 degrees per second, eccentric at a speed of 60 degrees per second, isotonic at 70% max, and max isometric contraction. All exercises were done with four sets to failure (voluntary fatigue) with 90 seconds rest between sets. Prior to and following each exercise modality three max isometric voluntary contraction at 90 degrees were performed, and peak isometric torque was recorded. Changes scores from pre to post were calculated then compared between modalities and sex using two-way repeated ANOVA with follow up lower-level ANOVAs for significance. RESULTS: There was an interaction affect (F = 2.77, P = 0.04), with males maintaining the same changes scores across modality (F = 0.33, P = 0.81), but females experience high changes scores as a result of isometric fatigue when compared to all other exercise modalities (F = 2.96, P = 0.04). CONCLUSION: Females and males do not experience the same responses to different fatiguing modalities. Males responded similarly (9.5 nm average decline in peak torque) across all modalities while females displayed the greatest decline following an isometric fatiguing modality (15.3 nm) when compared to all others (3.4 nm).