The influence of somatotype on acute and chronic responses to resistance exercise

Abstract

The relationship between somatotype and successful athletic performance is well established. Somatotype has also been linked to physiological function. This thesis assessed whether somatotype is related to anaerobic (particularly strength) performance and, how it might contribute to acute and chronic responses to resistance exercise in untrained people.

The first study demonstrated a link between somatotype rating and strength performance (Chapter 3). Mesomorphy was positively associated with upper- (chest press) and lower-body (back squat) strength performance. Mesomorphy was the best predictor of upper-body strength (31.4% of variance). A combination of mesomorphy and ectomorphy rating was the strongest predictor of 3 repetition maximum (RM) back squat performance (38.8% of variance). Chapter 4 investigated the reliability of categorising somatotypes from dominant ratings and concluded that categories should remain simple (e.g., only use primary dominant category), and be as precise as possible. Furthermore, with untrained participants, measures of muscle thickness (MT) were reliable when using ultrasound. Chapter 5 assessed whether there were any differences between simple somatotype groups in measures of MT. MT at the biceps brachii and biceps femoris was higher for mesomorphs than ectomorphs. However, baseline salivary cortisol and testosterone and resistance exercise-induced changes (acute responses) in these two measures were not different between somatotypes. The final study (Chapter 6) examined responses to an 8-week resistance training programme in untrained participants. Ectomorphs experienced an overall 26.4% greater increase in back squat 10RM strength over the training period compared to the mesomorphs. Mesomorphs experienced greater hypertrophy, particularly in the triceps brachii and biceps femoris. Measurement of muscle activity and changes in muscle blood flow were unable to help explain these findings. In summary, in an untrained population, somatotype is related to baseline strength performance, muscle size and adaptations to resistance training. Futhermore, somatotype can reliably assess strength performance outputs and responses to resistance training.

Date of Award	8 Jun 2021
Original language	English
Supervisor	Simon Jobson (Supervisor) & James Faulkner (Supervisor)