Combining strength training and cardiovascular exercise on the same day, known as concurrent training, is a common question when designing a fitness plan. Integrating these two distinct types of workouts is entirely possible and often highly effective for improving overall health and body composition. The feasibility of this approach hinges on strategically structuring the sessions to align with specific fitness objectives. A thoughtful approach ensures that one form of exercise does not significantly detract from the adaptations sought from the other.
Understanding the Interference Effect
Combining resistance and endurance training can sometimes create the “interference effect,” where the adaptations from one exercise type potentially limit the gains from the other. This effect is most often observed as a compromise in the development of maximal strength and muscle size compared to training with resistance work alone. The underlying mechanism involves a molecular signaling conflict within muscle cells.
Resistance training stimulates the mTOR pathway, responsible for anabolic processes like muscle protein synthesis and growth. Conversely, endurance exercise activates the AMPK pathway, which acts as an energy sensor and upregulates catabolic processes. When both types of exercise are performed too closely, the body receives conflicting signals, potentially blunting the peak muscle-building response.
The magnitude of this interference depends on the intensity and volume of the endurance work. High-volume, high-intensity cardio, particularly running, seems to cause a greater interference effect on lower-body strength than lower-intensity work or cycling. For individuals focused on general fitness, the interference effect is usually minimal and can be largely mitigated through smart programming.
Optimal Sequencing for Combined Workouts
When performing both modalities in a single training session, the order of exercises should be determined by the primary goal. For individuals aiming to maximize muscle size or strength, it is recommended to perform strength training first. This sequencing ensures that muscles are fresh and not fatigued by cardio, allowing for higher force production, better form, and the necessary intensity to stimulate muscle growth.
If the main objective is improving endurance performance, the cardio portion should come first. For example, a runner preparing for a race would want to complete their specific running workout while maximally fueled and rested. Performing high-intensity interval training (HIIT) or long, intense cardio immediately before heavy resistance training is discouraged, as the pre-fatigue increases the risk of injury and reduces lifting performance.
Low-intensity cardio, such as a brisk walk or light cycle, is an exception, as it can be used effectively as a brief warm-up before lifting or as a cool-down afterward. A warm-up of five to ten minutes of light cardio is beneficial for preparing the body for the heavier work ahead. If the cardio is moderate to high intensity, a separation time between the two types of exercise is needed, even within the same day.
Adjusting Training Schedules for Specific Fitness Goals
To minimize the interference effect for strength or hypertrophy, the most effective strategy is to separate the training sessions by several hours, ideally a minimum of six to eight hours. This separation allows the molecular signaling pathways to reset, giving the body time to recover and focus on the adaptations from the first session before initiating the second. For instance, a person prioritizing muscle gain might schedule a weightlifting session in the morning and a light cardio session in the evening.
For endurance-focused individuals, strength training should be scheduled away from long runs or high-intensity rides, or performed the day after a hard endurance session. This structure prevents the residual fatigue from the strength workout from compromising the quality of the subsequent endurance training. It is important to avoid training the same muscle groups intensely for both modalities in close proximity.
For those whose goal is general fitness, fat loss, or improved overall health, the convenience of combining sessions often outweighs the minimal compromise in peak gains. In these cases, consistent training and managing overall weekly training volume are the most important factors for success. Regardless of the specific goal, concurrent training significantly increases the body’s recovery demands, necessitating a greater focus on adequate sleep and consistent nutrient intake, especially protein and carbohydrates, to support both muscle repair and energy demands.