(2000) regarding the concept of exercise intensity. They stated that contrary to the classical thought which had defined exercise intensity as the magnitude of the load employed, research use only it must have been defined as the rate of the work performed. In the 1st and 6th phases, E30 and E0 generated significantly less EMG activity compared with NM (Figure 4). This result could be attributed to the necessity of less muscle effort to overcome the inertia of much lower external load in ER exercises during the early concentric and late eccentric phases of contraction. Nonetheless, the findings of the present study highlighted the effect of reducing the initial length of elastic material in achieving significantly higher muscle activation and applied lead by elastic resistance device (Figures 2 and and4).4).

The data demonstrated dramatically higher EMG values for E30 compared with E0 in all phases of contraction, except in the 3rd phase in which equal EMG readings was observed between the two modes of training. Based on similar finding, Hodges (2006) concluded that after reducing the initial length of elastic material, a shifting occurs in the distribution of muscle tension from late concentric to early concentric and from early eccentric to late eccentric range of motion. Accordingly, E30 exhibited significantly higher EMG than E0 in the 1st (48%) and the 6th (84.31%) phases. These data disclose the importance of reducing the initial length as an essential strategy to develop muscle activation by ER devices. Conclusion Many athletes rather use various modalities of resistance exercise (e.

g. free weights, pulley machines, isokinetic dynamometers, elastic resistance, etc) within their conditioning program with the prevailing view that each type of strength training offers a unique mechanical and physiological muscle stimulation (Welsch et al., 2005). On this basis, undertaking several types of resistance exercise might facilitate better development of the muscle performance. Based on equal average EMG between E30 and NM, the findings of the present study suggest that E30 could be an alternative to the use of NM in high exercise intensity (8-RM). However, since NM displayed higher EMG compared with E30 in the early concentric and late eccentric phases and E30 demonstrated higher muscle activation in the late concentric and early eccentric phases of contraction, a training protocol comprised of both modes of exercise seems to be ideal.

Acknowledgments For this investigation a research grant was provided by University of Malaya, Malaysia (PS008/2008C).
During the last 50 years, muscle strength training (ST) has been a major topic for coaches, athletes and researchers (Marques and Gonz��lez-Badillo, 2006). However, despite GSK-3 increasing professionalization, there is a paucity of research data concerning performance in elite athletes. Two main reasons for this may be suggested.