Combining running and strength training presents a common dilemma: which activity should come first? The order directly influences the results due to the “interference effect.” This effect suggests that combining endurance and resistance training too closely can diminish the adaptive benefits of one or both exercises. This happens because each exercise type activates different internal signaling pathways (AMPK for running, mTOR for lifting), and activating one can suppress the other. Ultimately, the correct sequence depends entirely on which fitness goal you prioritize for that specific training period.
Prioritizing Running: The Case for Cardio First
Running before lifting weights is the preferred strategy when the main goal is improving cardiovascular performance or endurance. Starting with cardio ensures that muscle glycogen stores are fully available for the aerobic effort. This allows the athlete to maintain a higher pace, cover a longer distance, and perform high-intensity running with maximal effort.
Beginning with a run also ensures the central nervous system is fresh, which is necessary for maintaining optimal running form and neuromuscular control. If stabilizing muscles are fatigued from prior resistance work, running performance can be compromised. This potentially affects stride efficiency and increases the risk of poor technique. For those training for a race, prioritizing the run first allows the body to adapt specifically to endurance demands.
The trade-off for this approach is a likely reduction in the quality of the subsequent strength training session. Running first leads to pre-fatigue, which depletes energy stores needed for maximal strength gains or power output. Studies show that performing cardio first diminishes the ability to lift heavy loads and complete repetitions with proper form. This limits the stimulus required for muscle growth (hypertrophy), as the muscles cannot be effectively pushed to their maximal capacity.
Prioritizing Strength: The Case for Resistance First
Placing strength training before running is the optimal sequence for maximizing strength gains, power development, or muscle hypertrophy. Beginning with resistance exercises ensures the muscles and nervous system are not fatigued by prior aerobic activity. This allows for the highest possible activation of muscle fibers, enabling the use of heavier weights and better maintenance of proper lifting technique.
Lifting heavier loads while fresh is crucial for maximizing strength adaptations, as this places the necessary mechanical tension on the muscle fibers. High central nervous system activation is also important for movements requiring high force and speed, such as Olympic lifts. Starting with strength training maximizes the mTOR signaling pathways associated with protein synthesis and muscle rebuilding.
When running is performed after a strength session, the body’s glycogen stores are already partially depleted, particularly after a strenuous leg workout. This causes the subsequent run to feel more challenging, as the body may rely more heavily on fat stores for fuel. However, the quality of the run may be compromised, especially for speed or long-distance efforts, due to residual muscular fatigue and depleted energy. The run will likely be slower and the perceived effort higher compared to a fresh run.
Optimizing the Session: Intensity, Duration, and Recovery
The most effective way to combine running and strength training involves strategic manipulation of intensity and duration to minimize the interference effect. If the goal is strength, the run preceding it must be low-intensity and short, acting only as a dynamic warm-up of about 5 to 10 minutes. Conversely, a high-intensity run, such as a sprint interval session, should not immediately precede a heavy lifting session on the same muscle groups.
The simplest solution to eliminate the interference between the two types of exercise is to separate them by at least six hours. Splitting the workouts into two distinct sessions allows the body’s signaling pathways and energy stores to recover and reset before the second activity begins. This strategy allows for a high-quality effort in both training modalities, maximizing the adaptive response to each.
Regardless of the chosen order, proper fueling and recovery are necessary for sustained progress. Consuming carbohydrates and protein after the first workout helps replenish glycogen and supports muscle repair before the second session. Monitoring recovery and ensuring enough rest between sessions is important, as the combined stress of concurrent training can increase the risk of overtraining or injury.