Anyone equipping a home setup with both a cardio machine and weights has to decide how the two fit together in a week. The research question is known as concurrent training: does adding aerobic work interfere with strength and muscle gains? Several meta-analyses have pooled the trials. This article summarises three, covering overall compatibility, session order and high-intensity interval training. The findings apply to healthy adults in the studies and do not amount to advice for people with injuries or medical conditions.
Overall compatibility: the 2022 meta-analysis
Schumann and colleagues included 43 studies that compared supervised concurrent aerobic and strength training, lasting at least four weeks, against an identical strength programme with no aerobic training. The pooled results were:
- Maximal strength: a standardised mean difference of -0.06 (95% confidence interval -0.20 to 0.09; P = 0.446), meaning no significant difference;
- Muscle hypertrophy: -0.01 (confidence interval -0.16 to 0.18; P = 0.919), again no significant difference;
- Explosive strength: -0.28 (confidence interval -0.48 to -0.08; P = 0.007), a significant reduction with concurrent training.
The authors conclude that concurrent training does not compromise muscle hypertrophy or maximal strength, but that explosive strength gains may be attenuated. The attenuation was more pronounced when both kinds of training were done in the same session (P = 0.043) than when sessions were separated by at least three hours (not significant). No significant effects were found for the type of aerobic training (cycling against running), the frequency of concurrent training (more or fewer than five weekly sessions), training status (untrained or active) or mean age (under or over 40).
For a lifter focused on muscle size and maximal strength, the meta-analysis found no significant cost from adding cardio. The included trials were supervised programmes.
Which goes first in the same session?
A 2018 systematic review and meta-analysis looked only at trials that compared strength before endurance with endurance before strength within the same session. Lower-body one-repetition maximum was significantly higher when strength training came first, with a pooled mean change of 3.96 kg (95% confidence interval 0.81 to 7.10 kg). The order made no difference to maximal aerobic capacity (pooled difference 0.39 ml per kg per minute, confidence interval -1.03 to 1.81). The authors conclude that putting strength first appears beneficial for lower-body strength while aerobic improvement is unaffected by order. The absolute difference is small and the interval wide, so it is a modest edge and not a rule.
Interval training and lower-body strength
A separate 2018 meta-analysis compared concurrent high-intensity interval training (HIIT) plus resistance training with resistance training alone. Muscle hypertrophy and upper-body strength changed similarly. Lower-body strength increased less with the combination (effect size -0.248, P = 0.049). Sub-analyses showed a trend, not statistically significant, for cycling HIIT to have a more negative effect on lower-body strength (-0.377, P = 0.074) than running HIIT (-0.176, P = 0.261). The authors suggest that any negative effect on lower-body strength may be reduced by using running-based HIIT and longer rest between the two modes, but they present this as a possibility. The 2022 meta-analysis, by contrast, found no significant difference between cycling and running for the overall outcomes, so the modality point remains unresolved.
Reading the evidence
- Consistent: hypertrophy and maximal strength held up under concurrent training in the 2022 pooled analysis.
- Some signal, some uncertainty: explosive strength and lower-body strength showed reductions in one or both analyses, with same-session training and cycling HIIT the suggested aggravating factors.
- Unresolved: the cycling against running contrast, since one analysis found a non-significant trend and the other found no significant moderator effect.
- Population: healthy adults in supervised trials. Extrapolating to home routines, older or clinical populations or elite athletes goes beyond what the reviews tested.
Turning it into a weekly plan
The reviews do not prescribe schedules, but they support some options. If explosive strength is not a priority, cardio and strength can be combined in one session without expecting a large penalty to muscle size or maximal strength. If it is, or if lower-body strength is a particular goal, separating sessions by several hours, doing strength first or choosing running-style intervals over cycling are the variations the analyses point to. Equipment placement can follow whichever schedule is chosen, and space and layout for keeping both in one room is covered in a separate guide.
Frequently asked questions
Will cardio stop me building muscle?
The 2022 meta-analysis found no significant difference in hypertrophy between concurrent training and strength training alone.
Should I lift before cardio?
One meta-analysis found slightly higher lower-body one-repetition maximum when strength came first, with no effect on aerobic capacity. The difference was modest.
Is HIIT on a bike worse for leg strength than running?
One analysis showed a non-significant trend in that direction. Another found no significant difference by aerobic type, so the evidence does not settle it.
The bottom line
Meta-analyses find that adding aerobic training to strength training does not significantly reduce muscle size or maximal strength in healthy adults, though explosive strength and, in one analysis of interval training, lower-body strength may gain less. Same-session training and strength-second ordering are associated with somewhat larger penalties. Equipment for both can therefore coexist in a home gym, and the main decision is scheduling rather than choosing one over the other.
Sources
- Schumann M et al., “Compatibility of Concurrent Aerobic and Strength Training for Skeletal Muscle Size and Function: An Updated Systematic Review and Meta-Analysis”, Sports Medicine, 2022
- “The physiological effects of concurrent strength and endurance training sequence: A systematic review and meta-analysis”, 2018
- “The compatibility of concurrent high intensity interval training and resistance training for muscular strength and hypertrophy: a systematic review and meta-analysis”, 2018