Acute effects of an intensity- versus load-controlled resistance exercise protocol on time-under-tension and physical work in older adults

AIM: Good muscular strength is decisive to manage tasks of daily life and to prevent falls. However, within recommendations of resistance training for counteracting the age-related loss of muscle mass, is a lack of information about training control. The aim of this study was to examine the effects of the implementation of two different protocols of training control (intensity-controlled through percentage [%] of maximum strength [1RM] versus repetition-controlled) during resistance training with older adults on time-under-tension (TUT) and physical work. METHODS: Fourteen older adults (age of 64.8±3.1 years) participated in this cross-sectional test-retest study and were measured at an interval of one week with two different protocols (intensity-controlled [CInt] versus repetition-controlled [CRep]) in the exercise ‘seated chest press’. RESULTS: Within CInt, the repetitions were reduced by about 49% across the sets; in CRep the load was reduced by about 20% across the sets. There was no significant difference with respect to executed repetitions and TUT between CInt and CRep, but there was a significant difference between single sets (p<0.001). Physical work demonstrated a significant reduction across the sets in CRep. Total physical work was higher in CRep (4934 N•m) compared to CInt (4349 N•m). CONCLUSION: A target number of repetitions with adapted load (repetition-controlled protocol) in consecutive sets was preferable if a high amount of physical work should be achieved and load intensity should not increase in subsequent sets. With the repetition-controlled protocol, high mechanical and metabolic stress is presumable, resulting in higher hypertrophic effects.