REF-1752 · Becerra-Patiño et al., 2026 · Frontiers in Sports and Active Living, · Paper · PubMed

Gym indoor-cycling (spinning) classes ran at about 78-81% of heart-rate reserve in two studies (80 and 53 riders), where Borg ratings correlated weakly with heart-rate reserve (r = 0.18, not significant, and r < 0.4); in 12 experienced men a class steered by RPE gave oxygen uptake closely correlated with classes steered by heart rate or by VO2: a systematic review of 17 small, mostly descriptive studies with no pooling, whose abstract claims rest on single studies

Main caveat: 17 heterogeneous studies, mostly single sessions, small samples, few controlled trials; nothing pooled.
limited, mixed evidenceMeasured on non-athletes to trained athletesRead in full

Becerra-Patiño and colleagues reviewed what indoor cycling classes do to physiological, cardiac and perceived-exertion responses in adults. From 1,607 records they included 17 studies, mostly single sessions measured in class or laboratory settings, and scored their quality with a 16-item checklist (11-15 points).

Class intensity was high: in one study riders spent 77.8% of heart-rate reserve with a mean Borg rating of 14.3 in the main phase, in another 80.6% with Borg 14.9; momentary oxygen uptake exceeded laboratory VO2max in 10 of 40 classes in a third.

Perceived exertion tracked heart rate poorly in two studies (the correlation between Borg and heart-rate reserve was 0.18, not significant, in riders with 6 months of experience, and below 0.4 in another class), whereas in 12 experienced men sessions steered by heart rate, by RPE or by oxygen uptake were closely correlated.

One study, whose results the text describes without numbers, found that sex, age, experience and wearing a heart-rate monitor did not affect heart rate or RPE, while sweat rate and rises in room temperature and humidity did. Training studies reported gains in cardiorespiratory fitness, for example 37.1 to 40.2 mL/kg/min after 36 sessions in 14 overweight young women.

The authors call indoor cycling high-intensity exercise that needs monitoring, and caution against generalising across such mixed studies.

Participants

17 studies, from 6 to a few hundred participants each (merged table cells make some sizes unreadable, e.g. one printed as "184116"); both sexes; mean ages about 22-51 where readable.
Populations: class participants of varying experience (novices, riders with 6 months of classes), physically active adults, sedentary men compared with 10 trained cyclists, overweight sedentary women, normal-weight and obese women, middle-aged women.
VO2max, where reported, about 32-48 mL/kg/min.

Protocol

Search: PubMed, Web of Science and Scopus, 30 April 2024, no date, language or design limits; two authors screened and extracted, disagreeing on 5% of documents.
Inclusion: original quantitative studies of indoor cycling in adults reporting at least one physiological, physical or anthropometric variable.
Quality: adapted Law et al. checklist, 16 yes/no items; sample size was justified in 4 of 17 studies.
Synthesis: narrative, by outcome domain (physiology, cardiac, biomechanics, perceived exertion).

Key Results

QuestionStudy (n where given)Finding as reported
How hard is a class?Muyor & López-Miñarro 2012 (80)Main phase 144 ± 14 bpm, 77.8 ± 7.2% of heart-rate reserve, Borg 14.3 ± 1.7
Muyor 2013 (53)Main phase 152 ± 14 bpm, 80.6 ± 7.1% of heart-rate reserve; Borg 14.9 ± 1.1, OMNI 7.2 ± 0.8
Battista 2008 (20 women)Mean 74 ± 14% and 66 ± 15% of VO2max in two classes; momentary VO2 above laboratory VO2max in 10 of 40 classes, for 5.4 ± 4.5 min
Does RPE track heart rate in class?Muyor & López-Miñarro 2012Borg vs %HR reserve r = 0.18, not significant (riders with 6 months of classes)
Muyor 2013Borg and OMNI vs heart rate and %HR reserve r < 0.4; Borg vs OMNI r = 0.82
Canário-Lemos 2020 (12 experienced men)Oxygen uptake in sessions steered by heart rate, by RPE and by VO2 correlated at r 0.977-0.992; the VO2-steered session was the most demanding
Soriano-Maldonado 2014An RPE learning protocol slightly improved the Borg scale's validity for self-regulating class intensity (no numbers in the review)
Rendos 2015 (11)Heart rate was a poor indicator of oxygen uptake, especially at high RPE (no numbers in the review)
What shifts heart rate and RPE?Barbado 2018 (size unreadable)Sex, age, experience and wearing a heart-rate monitor: no significant effect; estimated sweat rate and rises in room temperature and humidity: significant effect (no numbers in the review)
Ramos-Jiménez 2014Body temperature, mean blood pressure and heart rate higher without fluid than with water or sports drink (p < 0.01); water and sports drink did not differ
Training effectsBianco 2010 (14 overweight women)VO2max 37.1 ± 4.3 to 40.2 ± 4.6 mL/kg/min after 36 sessions; resting heart rate −6.5% and −9% after 24 and 36 sessions
PositionA study outside the 17 (39)Standing gave lower power (132 vs 198 W) and more left-right asymmetry than sitting at similar intensity
The abstract's statement that a 20-min class at 80-90% of maximal heart rate has positive effects is not traced to any study in the text.
The cardiac-rehabilitation improvements are attributed in the text to the Barbado study, which examined heart-rate and RPE factors; the supporting numbers come from a study outside the 17.

Practical Application

In a gym spin class, expect to work hard (roughly 78-81% of heart-rate reserve on average in two studies) and do not assume your RPE matches your heart rate there. In two class studies Borg ratings correlated weakly with heart-rate reserve; in experienced riders sessions steered by RPE or by heart rate came out alike. This is a review of small single-session studies.
Where this differs from [SYNTH-40]: the guide treats perceived effort as a validated instrument (its support is Foster's whole-session RPE against a heart-rate load score) and sets this review's class results beside it as bearing on in-class ratings, not on session RPE; in instructor-led spinning classes, in-class Borg ratings correlated weakly with heart-rate reserve in 80 riders with 6 months of classes (r = 0.18, not significant) and in 53 class participants (Borg and OMNI, r < 0.4), while in 12 experienced men a class steered by RPE gave oxygen uptake closely correlated with classes steered by heart rate or VO2 (r 0.977-0.992).The criterion in the two weak studies was heart rate, not lactate, a ventilatory threshold or power, and the review does not say whether the correlations were within or between riders. So in-class ratings did not follow heart rate in music-led classes; this is a validity result against heart rate, not evidence that RPE fails for a self-paced session or as session RPE.
A hot, humid room moves both heart rate and RPE: one study found room temperature, humidity and sweat rate shifted both, and riding without fluid raised heart rate and body temperature; compare indoor sessions only under similar conditions (SYNTH-40 already asks to compare like with like).
Learning the scale may help: an RPE learning protocol slightly improved how well ratings regulated class intensity in one study (REF-1612 found little difference between two ways of learning the Borg scale).
Not settled by this design: whether classes improve fitness more than other training; the training studies were small, uncontrolled or not described in enough detail in the review.

Limitations

17 heterogeneous studies, mostly single sessions, small samples, few controlled trials; nothing pooled.
The abstract's headline claims rest on single studies (the effect of sex, age, experience and monitor use) or on no study the text identifies (the 20-min, 80-90% maximal heart rate statement); the cardiac-rehabilitation finding is misattributed, and some cited evidence (rehabilitation, standing power, saddle height) comes from studies outside the 17.
RPE validity was judged against heart rate or heart-rate reserve, not against lactate, ventilatory thresholds or power.
Table 3 has merged cells that make some sample sizes and group values unreadable.
No funding received; no conflicts declared; the authors used generative AI for language editing.
How this entry was checked and changed
Why this level

quality appraisal read in full, but the included studies are mostly small single-session descriptive studies, nothing is pooled, the abstract's headline claims each rest on one study or on none that the text identifies, and the text attributes a cardiac-rehabilitation result to a study of something else