Ratings of perceived exertion (RPE) from a submaximal 20-m shuttle-run test accurately predict children's VO, but when should we stop the test?

Purpose: The purpose of the study was to explore the validity, test-retest reliability and affective responses of a submaximal 20-m shuttle-run test (20mSRT) stopped at 6 on the Eston-Parfitt (EP) scale. The secondary aim was to examine and compare two submaximal 20mSRT protocols with different RPE end points (EP6 vs. EP7) using previously published data.

Methods: Twenty-five children (16 boys; 13.4 ± 1.0 years; 162.1 ± 8.7 cm; 49.1 ± 6.6 kg) completed three exercise tests (graded exercise test [GXT], 2 submaximal 20mSRT). The EP scale and Feeling scale were used to measure RPE and affect, respectively. The two submaximal 20mSRTs were stopped after participants reported EP6. Individual speed-RPE relationships from the submaximal 20mSRTs were linearly regressed to predict peak speed and then used to estimate VO. Previously published data (n = 25) used comparable methods, except that the participants stopped at EP7.

Results: In the EP6 protocol, a two-factor repeated measures ANOVA revealed non-significant Test and Sex main effects (p > 0.05). Reliability analysis revealed intraclass correlation coefficient of ~ 0.7 (95%CI [0.432,0.867], p < 0.001) between the submaximal 20mSRTs. Significant differences in end-test affect between the GXT and submaximal 20mSRTs were found (p < 0.001), with GXT more negative. ANOVA revealed no significant differences in end-test affect between EP6 and EP7 protocols; however, frequency count analysis revealed EP6 to result in more positive end-test affect.

Conclusion: Submaximal 20mSRT utilising RPE may offer valid predictions in VO while minimising negative affect. Test end points of EP6 and EP7 both offer valid predictions in VO. EP6 may be more beneficial in avoiding negative affect, even though a reduction in test-retest reliability was observed.