Modification of the 20 metre shuttle run test (20 mst) for ice-sports

Introduction

The 20 MST1 is an over-ground aerobic field-test with established validity and utility2. The format of the test makes it ideal for use in ice-sports but the alternative nature of the surface (ice) leads to an over-estimation of the predicted VO2max3. The aim of this study was to modify the 20 MST for application to ice-sports.

Methods

A repeated measures design using proficient ice-skaters (n=72; 17.44±1.33 years) was adopted to determine velocity of motion, energy expenditure and mechanical efficiency on-ice (OI) vs. over-ground (OG). Based on observed differences and an overall variable-derived OI vs. OG ratio the test was modified by increasing the velocity of motion required for each level to increase the difficulty of the OI test. Subsequently, test-retest reliability and concurrent validity measures were determined.

Results

Mean OI vs. OG velocity of motion (5.990.72 vs. 5.750.63 m/s: p≤0.05), energy expenditure (10.512.95 vs. 14.044.86 kcal/min: p≤0.05) and mechanical efficiency index (6.831.49 vs. 4.920.59 p≤0.001) were significantly different. Accordingly the OI test velocity of motion for the initial stage was increased to 10.1 km/h and pro-rata for each subsequent level. Test-retest, OI reliability measures (n=15) for predicted VO2max (49.58.37 vs. 49.297.95 ml/kg/min) were highly consistent (r=0.87:p0.001). Similarly test-retest measures of predicted VO2max (n=10) with OG MST (48.096.25 ml/kg/min) vs. the adapted OI 20 MST (49.987.23 ml/kg/min), showed significant (r=0.73:p0.01) concurrent validity.

Discussion/ Conclusion

In conclusion the Over-ground 20 MST proved inappropriate for use on-ice. Modification of the starting velocity and a progressive increase in velocity for all subsequent stages renders the modified 20 MST for ice-sports a reliable and valid test for cardiorespiratory fitness with surface-specific utility.

References

[1]. Léger, L. A. et al. (1988). J Sports Sci, 6: 93- 101.
[2]. Van Mechelen, W. et al. (1986). Eur J App Physiol, 55: 503-506.
[3]. Kuisis, S. M. & van Heerden, H. J. (2001). AJPHERD, (S): 15-32.