Physiological and biomechanical responses during high intensity upper body exercise

Abstract

Fatigue during sport and exercise substantially affects the intensity and duration of an activity that can be maintained. Upper body exercise (UBE) despite contributing to sport, exercise and health outcomes has received relatively little attention particularly for high intensity exercise. Consequently, the mechanisms of fatigue during UBE are not fully understood. Therefore, the aim s of this thesis were to investigate a range of high intensity UBE protocols with respect to performance and the development of fatigue. In the first study participants (n = 13) completed four 30-s Wingate anaerobic tests (WAnT) against four different resistive loadings (2%, 3%, 4% and 5% body mass) thus potentially manipulating force production and cadence. Corrected peak power output (PPO) was independent of load (P > 0.05) and uncorrected PPO increased with load (P 0.05). All participants reached their maximum cardiorespiratory responses (oxygen uptake & heart rate; beats-min'1) at fatigue. The data suggested that prior to Tlim changes in EMG activation and movement patterns were related to the exercise intensity. In general, all EMG activity increased with intensity and exercise duration, with the kinematic data indicating that trunk rotational velocity rather than trunk stabilisation occurred throughout all trials. Overall, untrained participants altered their body movement to maintain PO between 30 & 120 s, however between 120 s & Tlim, no further significant changes occurred. In the final study, participants (n = 12) completed a 6-week arm crank training programme. Preliminary performance tests included a WAnT, V 02peak and 100% PMP test to exhaustion. Each test was repeated following the training programme. Corrected and uncorrected PPO and fatigue index (FI) increased in the WAnT test post training (P < 0.01, P < 0.05, respectively). Muscles of the shoulder (anterior deltoid & infraspinatus) demonstrated reduced activation following training (P < 0.05) with trunk rotational velocity increasing at corrected PPO during the WAnT (P < 0.01). Therefore, increases in WAnT PO may be related to changes in technique rather than muscle activation. Following training there was a significant increase in PMP (P < 0.01) during the V 02peak test and a significant increase in Tlim (P < 0.01) for the repeated 100% PMP test. Following training there was a significant decrease in triceps brachii EMG activation (P < 0.05), changes in external oblique activation (P < 0.001) at 120 s and a significant increase in trunk rotational velocity at 30 s (P < 0.05). Although at Tim, the kinematic responses were the same. The results of this training study indicated that changes in performance were due to physiological adaptations and changes in technique. The three studies have demonstrated the importance of changes in EMG activity, trunk rotational velocity, and technique to arm crank PO rather than specific physiological changes alone which has implications for the use of arm cranking in testing, training and performance outcomes