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You will have had this conversation more than once. A client wants to be stronger but also wants to run a half marathon, or wants to keep cycling at the weekend but also wants to build noticeable muscle, or wants to do CrossFit two evenings a week and have time for a couple of hard turbo sessions on top. They ask the question every PT eventually has to answer: can I train for both without one cancelling the other out?
For decades the standard reply has been a polite version of “not really.” Coaches grew up with the idea that strength and endurance training fundamentally interfere with each other, that one set of adaptations crowds out the other and that anyone serious about either should pick a lane. That rule of thumb has shaped programming choices, gym timetables and athlete advice ever since the original interference research landed in the 1980s.
The recent evidence base tells a more nuanced story. A wave of 2022 to 2025 systematic reviews and meta-analyses has tested the old assumption against larger participant pools, modern training methods and finer-grained mechanistic data. The results showed that concurrent training, structured intelligently, allows clients to develop strength, hypertrophy and aerobic capacity in parallel without anything close to the trade-off the early studies implied. There are conditions to that statement, and the conditions you will find quite interesting.
The whole concurrent training conversation traces back to a 1980 study by Robert Hickson at the University of Illinois. Hickson took three groups, one training strength only, one training endurance only and one training both, all five days a week for ten weeks. The strength-and-endurance group made similar VO2max gains to the endurance-only group, but their strength gains plateaued and ultimately fell behind the strength-only group after about the eighth week (Hickson, 1980).
That paper coined the term “interference effect” and the conclusion stuck. Trainers and coaches for the next forty years built programmes on the assumption that combining the two would always cost something on the strength side.
What is easy to miss when reading the original study is how aggressive the protocol was. Hickson’s participants were doing five days a week of each modality, often in the same day, with limited recovery between sessions. That dose is well beyond what almost any general-population client, or even most athletes, would attempt. The interference effect, in other words, was demonstrated at the extreme end of training stress, not in the more moderate concurrent loading patterns that real-world programmes use.
The most authoritative recent synthesis comes from Schumann and colleagues, whose 2022 updated meta-analysis in Sports Medicine pulled together 43 randomised trials covering more than 1,000 participants. Their conclusion was that concurrent aerobic and strength training does not compromise muscle hypertrophy or maximal strength development when compared with strength training alone (Schumann et al., 2022). Lower-body strength and lean mass gains were essentially indistinguishable between groups.
A 2026 umbrella review by Held and colleagues built on this, examining 17 meta-analyses representing 144 individual studies and 1,492 participants (Held et al., 2026). Concurrent training produced comparable improvements in aerobic capacity to endurance training alone, and comparable improvements in hypertrophy to strength training alone. The interference effect, as a general phenomenon affecting general clients, is much smaller than the original literature suggested.
Where the modern evidence does flag real concern is around explosive strength or power. Power adaptations appear to be more vulnerable to concurrent training than maximal strength or hypertrophy, particularly when aerobic and resistance sessions are done within a few hours of each other. If your client is a sprinter, a jumper or anyone whose performance depends on rate of force development, concurrent training plans need a different shape than a general fitness or hybrid client.
The second area where the evidence is clear is in the type of aerobic work. A 2022 systematic review and meta-analysis in Sports Medicine on muscle fibre hypertrophy found that combining resistance training with running, but not with cycling, produced significant decrements in both hypertrophy and strength outcomes (Lundberg et al., 2022). Running’s higher eccentric loading, longer foot-strike duration and greater muscle damage profile appear to compete more aggressively with the recovery demands of resistance training. Cycling appears to slip alongside resistance work much more cooperatively.
The mechanistic story underneath this sits at the level of two opposing signalling pathways inside the muscle cell. Resistance training preferentially activates the mTOR pathway, the master regulator of protein synthesis and muscle growth. Endurance training preferentially activates AMPK, a metabolic sensor that drives mitochondrial growth and aerobic adaptation. AMPK activation can suppress mTOR signalling, which is the molecular argument for why heavy cardio loaded right before or right after a lifting session might blunt the muscle-building response.
A 2015 paper from the School of Sport and Exercise Sciences at Liverpool John Moores University by Jamie Pugh and colleagues looked at this directly in untrained skeletal muscle (Pugh et al., 2015). They measured acute signalling responses to a session combining resistance training with high-intensity interval cycling. Both mTOR and AMPK pathways activated, but the resistance-induced anabolic signalling was preserved despite the concurrent cardio. The interference at the molecular level was less stark than the early hypothesis predicted, particularly when adequate recovery time separated the two stimuli.
Coffey and Hawley’s influential 2017 paper in The Journal of Physiology, which has shaped much of the modern thinking on concurrent training, framed the question well: the molecular bases of adaptation are distinct but not strictly antagonistic. They become genuinely incompatible only under specific conditions of timing, dose and individual capacity (Coffey and Hawley, 2017).
For years the standard programming advice was to do resistance training first if strength was the priority, and endurance training first if endurance was the priority. The reasoning was that whichever adaptation you wanted most should not be diluted by pre-fatigue from the other modality.
Murlasits and colleagues tested this in a 2018 meta-analysis of intra-session sequence and found that the order of training has a much smaller effect than the old rule suggested (Murlasits et al., 2018). Strength-first and endurance-first sessions produced similar strength and aerobic adaptations across the studies reviewed. The body recovers from each stimulus over the hours and days that follow, and the dominant variables turn out to be overall weekly volume, recovery between sessions and the client’s adherence, not which exercise comes first within a single session.
The practical implication is that you have more flexibility than the old rule suggested. If a client trains better with a hard cardio session as their warm-up because they feel mentally locked in afterwards, that is a better choice. If they prefer to lift first because that is when they are freshest for heavy loads, that also works. The order is less important than whether each session was done with appropriate intensity and whether the overall weekly load was sensible.
What does appear to matter is the time between concurrent sessions when they happen on the same day. The interference effect at the molecular and performance level is most pronounced when sessions are separated by less than three hours. Once the gap stretches to six hours or longer, or when sessions sit on different days, the interference effect largely dissipates.
For most general clients, this is good news. Two separate sessions in a day is uncommon. Most clients lift twice a week, do cardio twice a week and the two sit on different days entirely. That naturally separates the stimuli and gives the body time to handle each one without the competing signalling cascades overlapping.
For athletes and committed hybrid trainers running double-day schedules, the recovery window is where programming care pays off. A morning conditioning session followed by an afternoon strength session, with at least six hours between them and a deliberate refuelling window in the middle, sits much closer to the additive-adaptation end of the spectrum than to the interference end.
Most of the clients on your books are probably not hybrid athletes preparing for HYROX or training for a powerlifting meet alongside a marathon. They are general-fitness clients who want to be strong, lean, fit and able to keep up with their lives. The 2024-25 evidence makes the programming side of this simpler than the historic interference effect literature implied.
Weekly Volume
A sensible weekly template for most clients is two to three resistance sessions and two to three cardiovascular sessions. Below that level, neither adaptation gets enough stimulus. Above that level, recovery starts to become the limiting factor and the interference effect starts to creep back in. Aim for total training frequency of four to six sessions per week and use whatever blend of strength and cardio suits the client’s goals.
Same-Session Versus Separate-Day
If time pressure forces concurrent sessions onto the same day, separate them by at least six hours where possible. If that is not possible, sequence them so the priority adaptation goes first while the client is fresh, and keep the second modality at moderate intensity rather than going all-out twice.
For clients whose schedule allows, separate-day programming is simpler. Mondays and Thursdays for strength, Tuesdays and Saturdays for cardio, with the other days as rest or active recovery. This is the default that gives the cleanest signal for both adaptations and is what the evidence supports as the lowest-friction approach.
Sample Weekly Template
The table below shows a workable concurrent training week for a general fitness client.
| Day | Session | Notes |
|---|---|---|
| Monday | Lower-body strength | Compound lifts, 3 to 5 sets, moderate to heavy loads |
| Tuesday | Steady-state cycling, 40 to 60 minutes | Zone 2 heart rate, no eccentric loading |
| Wednesday | Rest or mobility | Light yoga or walking |
| Thursday | Upper-body strength | Compound lifts plus accessory work |
| Friday | Interval cycling, 25 to 30 minutes | 4 to 6 hard intervals with full recoveries |
| Saturday | Full-body strength | Slightly lower intensity, technique-focused |
| Sunday | Rest | Full recovery |
Notice the cardio is deliberately bike-based in this template. That is not an absolute rule. If the client prefers running, simply build in lighter mileage and avoid hard intervals within 24 hours of a lower-body lift to reduce the eccentric overlap that the running-versus-cycling research flagged.
There is one client profile where the modern evidence still backs caution: the power athlete or anyone whose sport depends on explosive output. Sprinters, jumpers, powerlifters working on speed-strength, throwing-sport athletes and anyone training rate of force development as a primary outcome should treat concurrent endurance work more carefully.
For these clients, the recommendation from the recent literature is to keep aerobic work to genuinely low volumes (one or two sessions a week, kept short and moderate-intensity), separate it from the priority lifting work by at least 24 hours and bias the cardio choice towards cycling or non-impact modalities. Heavy endurance running close to a peak power phase has consistently shown attenuating effects on explosive strength gains.
The other group worth flagging is older adults who are training for power as the primary outcome. Recent reviews on older-adult populations have noted that the interference effect on power is more pronounced in this group, partly because their recovery capacity is reduced and partly because the rate-of-force decline associated with ageing is already on a steeper trajectory.
The shorthand of the last forty years was that strength and cardio cancel each other out. Recent evidence however is more useful and more permissive. Concurrent training is compatible with both hypertrophy and aerobic capacity for almost every client we see, provided the weekly volume is sensible, the sessions are separated by enough time when they sit on the same day and the choice of cardio modality respects the client’s recovery profile.
The two genuine caveats are power-focused clients, where concurrent endurance work still warrants caution, and the same-session timing question, where six hours of separation is the threshold beyond which interference largely disappears. Outside those scenarios, the old advice to pick a lane is no longer supported by the data.
Many of us find our clients want it all: stronger legs, a faster 5k, more muscle, better cardio. The good news from the recent research is that you can build them strong, fit, lean and capable in parallel. The programming work sits in dose management and recovery, not in choosing between the two.
The recent evidence on concurrent training is only important if you have the broader programming toolkit to apply it well. Combining strength and cardio intelligently for individual clients calls on several skill areas in one go: programming for hypertrophy and strength, sequencing aerobic work by modality, understanding recovery and load management and knowing when to pull back. That breadth is exactly what specialist CPD opens up.
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