Changes In Rapid Torque Development Following Different Resistance Training Modalities To Fatigue

Rapid torque measurements have been shown to be more sensitive to fatigue than later torque measurements. How these rapid torque characteristics are affected by different modalities is still unclear as some fatiguing tasks like isometrics may be more neurologically fatiguing while isotonic may be more metabolically fatiguing. PURPOSE: To determine what modality of exercise (isometric, isotonic, eccentric, isokinetic) elicits the greatest fatiguing response. 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 all participants were free of knee pain or injury. Participants visited the lab on 4 different occasions and performed unilateral knee extensions with different modalities on each lab visit day using 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 completed with four sets to failure (voluntary fatigue) with 90 seconds rest between sets. Prior to and following each exercise modality, three max isometric voluntary contractions at 90 degrees were performed and rapid torque development (RTD) was calculated at 50,100 and 200 ms. Changes in 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 no interaction affect for any of the RTD times points (F ≤ 1.89, P > 0.05), there was no main affect for modality for any of the RTD time points (F ≤ 1.53, P > 0.05), or a main affect for sex at any of the time points (F ≤ 1.85, P > 0.05). CONCLUSION: All rapid torque development responded similarly across exercise modality and sex. The RTD at 50 ms averaged a 245 nm/sec decline across all four modalities while RTD at 100 and 200 ms averaged a decline of 212 and 99 nm/sec, respectively. Overall males and females responded similarly to different fatiguing exercise modalities with no modality in particular being more fatiguing than the other.