Torque changes over a ten-year period in south african army recruits

Introduction

Physical fitness forms an important component of total wellness. It is widely accepted that hypokinetic diseases are becoming more prevalent. Thus, by observing changes in the fitness level of a nation, important trends in lifestyle can be identified. The aim of the study was to investigate the changes in the isokinetic torque values and body composition of South African (SA) army recruits over a ten-year period, by comparative analysis of previous research findings [1,2].

Methods

A cross-sectional analytical quantitative design of two studies conducted in 1985 (n=100) and 1995 (n=439) respectively on SA male army recruits was used to investigate isokinetic torque and body composition changes. Somatotyping was used to describe body composition [3]. Concentric peak torque (non-gravity corrected) of the non-dominant limb was determined with a Cybex II and Cybex 340 isokinetic dynamometer. Three movement patterns were investigated: i) knee flexion and extension (60°/s), ii) elbow flexion and extension (60°/s), and iii) ankle dorsi flexion and plantar flexion at 30°/s [1,2]. Differences between the two studies were analysed through descriptive statistics only since the raw data of the 1985 study was absent, and any difference of 15% or more between the two sample averages was considered significant.

Results

An improvement of 28% was observed for absolute knee flexion torque (Nm) and the knee flexion/extension ratio (%) showed an increase of 18%. An increase of 15% was seen in the endomorphic component, while both relative elbow flexion and extension torque (Nm/kg) values showed a decrease of 16%. No significant differences were observed for the ankle joint.

Discussion/ Conclusions

The increase seen in the endomorphic component or fat mass may reflect the fact that activity levels in SA have decreased due to the introduction of television in 1975, increased levels of saturated fats in the SA diet, and the abolishment of physical education as a school subject. The improvements seen in absolute knee flexion torque (Nm) could possibly be attributed to a 5.2% increase in body weight (71.5 kg vs. 67.8 kg) from 1985 to 1995, while the improvement in the knee flexion/extension ratio could not be explained. These increases are however, in contrast with the decreases shown in relative elbow flexion and extension torque (Nm/kg). The changes in SA lifestyle, reflected by an increased fat mass, are probably responsible for this finding.
Conclusion
The relative elbow torque values of SA army recruits have deteriorated over a ten-year period, possibly due to an increase in fat mass, resulting from lifestyle changes.

References

[1]. Lategan, L. (2002). Normative isokinetic torque values for rehabilitation in SA. Unpublished doctoral thesis. Pretoria, University of Pretoria.
[2]. Moolman, J. (1985). Kragwaardes van die onderste en boonste ledemate van nasionale dienspligtiges in die SA Leër. Unpublished master’s dissertation. Stellenbosch, University of Stellenbosch.
[3]. Carter, J.E.L. (1980). The Heath-Carter somatotype method. San Diego, San Diego University Press.