Mixed
Performing resistance training before high-intensity interval training (RT+HIIT) in same-day concurrent sessions attenuates lower-body power development (countermovement jump displacement, force, and power) compared to resistance-only training, whereas aerobic fitness and strength gains remain comparable.
If you train resistance and cardio on the same day and care about explosive power (like jumping or sprinting), do your weights first. Doing cardio first will blunt your power gains, even if your strength and endurance improve normally. Keep the gap between sessions to at least 3 hours if possible.
Compared to RT, RT+HIIT attenuated CMJ displacement (mean difference ± 90%CI, -5.1 ± 4.3%), force (absolute: -8.2 ± 7.1%) and power (absolute: -6.0 ± 4.7%).
Why this rating
Randomized controlled trial with adequate sample size (n=29), clear control group (RT-only), and ecologically valid 3-hour separation, though limited to moderately-active men.
Source
Order of same-day concurrent training influences some indices of power development, but not strength, lean mass, or aerobic fitness in healthy, moderately-active men after 9 weeks of training
Matthew J-C Lee et al. · PLoS ONE · 2020
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