Participation in physical activity (PA) in the US is low, as less than 50% of adults achieve at
least 150 min/wk of moderate-intensity continuous training (MICT) or 75% of vigorous-intensity
exercise (CDC, 2017). Low participation in PA is a problem because inactivity is one of the
leading causes of premature mortality (Mokdad et al., 2004). The current recommendations
including high volume MICT and resistance training require about 4 h/wk which is unrealistic for
adults, as “lack of time” is cited as the primary reason for low PA (Trost et al., 2002). REHIT is a
form of sprint interval training that requires only 10 minutes per session and elicits similar health
related adaptations as chronic MICT (Cuddy et al., 2019). However, there are concerns that it
may be too aversive (Ekkekakis et al., 2011). PURPOSE: To compare changes in affective
valence and enjoyment to a single session of REHIT in adults with varying fitness level.
METHODS: 85 healthy non-obese subjects participated in the study. Baseline testing consisted
of incremental cycling to assess VO2max during which participants were familiarized with
reporting Rating of Perceived Exertion (RPE) and affective valence. The VO2max results were
used to group subjects into above and below average cardiorespiratory fitness (CRF).
Subsequently, they completed a REHIT session consisting of two 20-second sprints
interspersed with 3 minutes of active recovery. During the session, heart rate (HR), RPE,
affective valence, blood lactate concentration (BLa), and enjoyment were assessed. RESULTS:
RPE increased and was highest after sprint 2 (p < 0.001), but there was no significant group X
time interaction (p = 0.41). Affective valence decreased but remained positive in both groups (p
< 0.001), and there was no significant difference between groups (p = 0.86). Enjoyment was
high in both groups (93.2 ± 20.8 vs. 91.1 ± 16.4 in above and below average CRF, respectively),
and there was no significant difference between groups (p = 0.64). BLa increased 9-fold during
REHIT (p = 0.001); however, there was no significant difference between groups (p = 0.64).
CONCLUSION: There was no effect of CRF on perceptual changes in response to REHIT,
indicating that low-volume SIT may be suitable for individuals with below average CRF.