The effect of balance and strength training on muscle activation, strength and standing balance
Faculty of Computing, Health and Science
School of Exercise and Health Sciences / Centre for Exercise and Sports Science Research
Introduction: Strength training has, for many years, been used by athletes to improve sports performance. Recently, balance training has become popular to assist in the reduction of knee injuries. However, the underlying neuromuscular changes resulting from these different training modes have not been evaluated in a consistent, comprehensive fashion. This paper aimed to establish the neuromuscular effects from different types of training by investigating how different training affects the knee muscle activation patterns and strength on isometric and isokinetic tests as well as standing balance. The training programs were: (1) Machine-Weights; (2) Free-Weights; (3) Balance-Training; and (4) Machine-Weights + Balance training. Identifying these effects will assist in our understanding of mechanisms which change from training and their possible effect on joint stability. Methods: Fifty healthy subjects were allocated to either a control group or one of four 12-week training programs. Subjects were tested pre and post training. Muscle strength and electromyography (EMG) for each subject were measured whilst performing isometric, eccentric and concentric leg extension and leg flexion exercises with the preferred limb on an isokinetic dynamometer. Stability tests were also conducted to assess changes in standing balance. The maximum load that subjects could lift for only three repetitions (3RM) on their specified training apparatus was also measured. Results: All strength training groups increased strength specific to the training equipment used in their respective programs. The Free-Weights group experienced improvement on isometric and quadriceps eccentric strength, and decreases in co-contraction and greater agonist activation on the isometric and isokinetic tests. The Machine-Weights group did not experiences any significant changes in strength measures on the isometric and isokinetic tests, however there were some decreases in co-contraction. Balance training resulted in increased hamstring muscle activation and flexor torque, as well a decrease in extensor torque. Improvements in the standing balance measures were also seen groups that underwent balance training (reported changes are significant, p < 0.05). Conclusion: Different types of training elicit a variety of neuromuscular changes on controlled tests. These provide greater understanding of the mechanisms resulting from training, which have the potential to map over into sporting manoeuvres, with possible effects on joint stability and support. However, smaller than expected changes were measured, especially with no significant strength increases measured on the isometric and isokinetic tests following some training, even though improvements in strength were observed on the training equipment. This indicates that these tests are not sensitive all outcome measures.