Author(s): MEYLER, S., MUNIZ-PUMARES, D., BOTTOMS, L., WELLSTED, D., Institution: UNIVERSITY OF HERTFORDSHIRE , Country: UNITED KINGDOM, Abstract-ID: 1975

INTRODUCTION:
Prescribing exercise intensity relative to maximum oxygen uptake (V̇O2max) is consistently shown to poorly control and normalise exercise intensity among individuals [1]. Alternatively, prescribing exercise intensity relative to critical power (CP) is shown to reduce the variability in exercise tolerance and acute physiological responses among individuals [2]. This might have important implications on the manifestation of subsequent adaptations to training such as changes in cardiorespiratory fitness [3]. The aim of this study was to compare the magnitude and variability in changes in cardiorespiratory fitness following exercise training prescribed relative to V̇O2max and to CP.
METHODS:
Twenty-seven healthy individuals volunteered to take part in the study. All individuals completed a maximal ramp exercise test (GXT) and three constant work rate trials (CWR) on a cycle ergometer for the determination of V̇O2max and CP, respectively. Exercise tests were repeated midway and at the end of the intervention. Individuals were then randomised into a threshold-group (THR; n=10), where six weeks of exercise training was completed at an intensity prescribed relative to CP; a traditional group (TRAD; n=10), where the exercise training was prescribed relative to V̇O2max; or a non-exercising control group (CON; n=7). Exercise training consisted of two interval training sessions and one continuous exercise session per week.
RESULTS:
From pre- to post-intervention, V̇O2max increased by 13% (4.3 ± 3.1 mL·kg-1·min-1 [95% CI: 1.4 to 7.1]; P=0.005) in THR, 9% (2.9 ± 2.0 mL·kg-1·min-1 [95% CI: 1.1 to 4.8]; P=0.004) in TRAD, and was unchanged in CON (2.0 ± 2.2 mL·kg-1·min-1 [95% CI: -0.9 to 4.8]). Five (50%), three (30%), and two (29%) individuals experienced a meaningful increase in V̇O2max of ≥3.5 mL·kg-1·min-1 in THR, TRAD, and CON, respectively. No difference was observed in the variability of V̇O2max changes between groups (P>0.05). No significant relationships were observed between the relative change in V̇O2max and individual or training characteristics in either exercise group (P>0.05).
CONCLUSION:
Following six weeks of exercise training, superior increases in V̇O2max appeared to be elicited following THR compared to TRAD. Additionally, a greater proportion of individuals experienced a meaningful increase in V̇O2max following THR compared to TRAD. Future primary research with adequate power is warranted to investigate whether this observation holds true in a larger sample. If consistent, these data support the use of critical power, over V̇O2max, when prescribing exercise intensity.