Little is known about the muscle function capabilities of trained middle-aged males and how they differ to younger counterparts. Accordingly, the overall aim of the research documented in this thesis was to compare the acute muscle function responses to resistance exercise in middle-aged and young resistance trained males. The first study (Chapter 3) examined the intra- and inter-day reliability of an ecologically valid device (FitroDyne rotary encoder) for measuring upper and lower-body muscle function during three popular multi-jointed resistance training exercises (bench press, squat, and bent-over-row), and confirmed that it was capable of detecting moderate changes in muscle function across a range of submaximal loads. In the second study (Chapter 4) the load-velocity and load-power relationships were investigated during the same exercises among 20 young (age 21.0 ± 1.6 y) and 20 middle-aged (age 42.6 ± 6.7 y) resistance trained males, and it emerged that, despite their regular training, the middle-aged males were unable to achieve velocities at low external loads and peak powers at all external loads as high as the young males across a range of external resistances.
Study three (Chapter 5) proceeded to compare the internal (heart rate (HR), OMNI-ratings of perceived exertion (RPE) and sRPE) and external (peak velocity and power and volume load) loads experienced during high volume squatting exercise, and the fatigue responses among nine young (age 22.3 ± 1.7 years) and nine middle-aged (age 39.9 ± 6.2 years) resistance trained males. The findings highlighted that internal, but not certain markers of external (peak power and volume load), load responses can be monitored during exercise in a like manner between these age groups. Moreover, compared to young resistance trained males, middle-aged males can expect greater decrements in peak power after lower-limb resistance exercise. In the final study (Chapter 6), the time-course of recovery in nine trained young (age 22.3 ± 1.7 years) and nine trained (39.9 ± 6.2 years) and nine untrained (44.4 ± 6.3 years) middle-aged males after high volume lower-body resistance (muscle damaging) exercise was investigated. Of practical importance, it emerged that compared to the young males, the trained middle-aged males experienced greater symptoms of muscle damage and an impaired recovery profile, the implication of which is the need for trained middle-aged males to adopt strategies to enhance their recovery. Furthermore, both middle-aged groups experienced similar symptoms of muscle-damage, albeit the untrained group demonstrated greater losses in peak power at low and high external loads.
For the first time, the current research has determined that middle-aged males, despite regular resistance training, are subject to losses in peak velocity and power output across a range external loads, compared to young males. When undergoing lower-body resistance training to ameliorate these decrements, applied practitioners can use internal load markers and peak velocity, but not peak power or volume load, to monitor trained young and middle-aged males alike. Furthermore, the muscle damage response (24 to 72 h), and losses in peak power (0 to 72 h), after lower-body resistance exercise are greater in trained middle-aged than young males. Consequently, future research should seek to corroborate these observations in upper-body exercise and determine the effectiveness of strategies (e.g. nutritional intake) to enhance recovery in middle-aged males.