The effect of repetition tempo on cardiovascular and metabolic stress when time under tension is matched during lower body exercise

Purpose To investigate the effect of repetition tempo on cardiovascular and metabolic stress when time under tension (TUT) and effort are matched during sessions of lower body resistance training (RT). Methods In a repeated-measures, cross-over design, 11 recreationally trained females ( n = 5) and males ( n = 6) performed 5 sets of belt squats under the following conditions: slow-repetition tempo (SLOW; 10 reps with 4-s eccentric and 2-s concentric) and traditional-repetition tempo (TRAD; 20 reps with 2-s eccentric and 1-s concentric). TUT (60 s) was matched between conditions and external load was adjusted so that lifters were close to concentric muscular failure at the end of each set. External load, total volume load (TVL), impulse (IMP), blood lactate, ratings of perceived exertion (RPE), HR, and muscle oxygenation were measured. Results Data indicated that TVL ( p < 0.001), blood lactate ( p = 0.017), RPE ( p = 0.015), and HR ( p < 0.001) were significantly greater during TRAD while external load ( p = 0.030) and IMP ( p = 0.002) were significantly greater during SLOW. Whether it was expressed as minimal values or change scores, muscle oxygenation was not different between protocols. Conclusion When TUT is matched, TVL, cardiovascular stress, metabolic stress, and perceived exertion are greater when faster repetition tempos are used. In contrast, IMP and external load are greater when slower repetition tempos are used.