One of the most common questions I encounter almost every day as a trainer is what to do first, weight training or cardio, regardless of the fitness goal. While some experts recommend doing cardio before a weight training session, other arguments favour performing cardio after weight training. Before moving into the research studies, we must understand two basic terms- concurrent training and interference-effect, which are explained below-
Sportsmen worldwide need to develop strength and endurance to excel in their sport. Aerobic exercise is often performed in combination with resistance training to maximize fat loss and sports performance. this strategy is known as “concurrent training.” In other words, doing cardio and strength training on the same day.
According to a 2018 study in the journal Sports Medicine, British researcher Lee Eddens & team (https://bit.ly/3dX6m0C), “Concurrent training is defined as the simultaneous integration of both resistance and endurance exercise within a coherent training plan.”
Some evidence suggests that the introduction of aerobic training into a regimented weight training program has the potential to compromise muscle growth. This phenomenon is known as the chronic interference effect.
According to a study published in the European Journal of Applied Physiology and Occupational Physiology by Robert Hickson, “the Interference effect is the decrease in strength development during a concurrent training model compared to that following isolated resistance training.”
Dr. Robert Hickson conducted this study on three different groups-
Dr. Robert Hickson found that the group who did concurrent training gained as much muscle mass as the strength group but gained significantly less strength. Similarly, the concurrent training group gained as much endurance as the cardio-only group. In simple words, adding cardio before or after a resistance training workout had little to no impact on muscle growth but a slight decrease in strength gain. Interestingly, strength training had no adverse effect on endurance.`
But like other studies, this study also had some limitations. For example, the concurrent training group performed heavy 80-100% of IRM lower body strength workouts 5 days per week and 4 hours of high-intensity cardio, which most people won’t do because it is not attainable in the long run. However, the concurrent training group had a more significant fat loss (2%) than the strength-only group.
Research indicates that concurrent training can harm muscular growth, but many studies have shown no evidence of an interference effect. Following factors can contribute to the interference effect (https://www.strongerbyscience.com/concurrent-training-part-2/)-
1. Molecular signalling- Muscle hypertrophy occurs when muscle protein synthesis rate exceeds muscle breakdown rate. Resistance training and protein consumption are the two primary stimuli of muscle hypertrophy. Resistance training results in the signalling of various proteins, such as mTor, which is responsible for MPS elevation, whereas endurance exercises stimulate other proteins, such as AMPK- Akt. This hypothesis states that endurance exercise-induced proteins can inhibit mTor functions, affecting MPS rate after training.
2. Muscle fiber type- There are two muscle fibers- slow-twitch (type 1) and fast-twitch (type 2) muscle fibers. Fast-twitch muscle fibers are further classifieds as type IIa and type IIc. Slow-twitch muscle fibers are primarily used when performing low-intensity steady-state activities such as running or high-repetition weight training. On the other hand, fast-twitch muscle fibers are those which are responsible for producing greater force at a higher intensity. High-intensity weight training recruits both types of muscle fibers. Still, the activation of the slow-twitch muscle fibers is not as much as the activation of the fast-twitch muscle fibers during high-intensity resistance training. What happens when we train both strength and endurance simultaneously?
3. The time between bouts of endurance and resistance training- The time difference between these two types of training affects muscle growth differently in the short and long run. Acute factors associated with aerobic training may interfere with weight training capacity. In simple terms, high-intensity aerobic training can cause residual fatigue and muscle glycogen depletion, leading to compromised resistance training sessions. If you want to experience this, I want you to do 30 minutes of HITT and perform heavy squats right after that. I promise you won’t be able to lift as much as you usually lift on your squat day. This decrease in intensity or volume will render muscular gains. It will not happen with one odd HITT session combined with resistance training. Still, this reduction in the intensity and volume accumulated over a long time can be detrimental to your progress. Another hypothesis known as chronic interference alleges that trained muscles can not simultaneously adapt optimally morphologically and metabolically to both strength and endurance training.
As we know, aerobic training performed around resistance training can negatively impact muscle gain in the long run, especially among well-trained people. A meta-analysis by Wilson and Colleagues showed that effect size for muscle gain was reduced by 50% among people when aerobic training was added to their resistance training program.
However, many studies show that cardio training may enhance muscle growth if appropriately added to a resistance training program. For example, adding cycling to strength training actually produces more muscle mass in the lower body than strength training alone.
Now the questions here are what people should do if their main goal is gaining muscle mass, but they also want to work on their endurance? When should they do their endurance training- before or after a resistance training session?
Following are some of the evidence-based recommendations from top researchers and fitness experts:
References
Chopra, A. (2020). CARDIO OR STRENGTH TRAINING. Delhi: e-book.
Schoenfeld, B. (2021). Science and development of muscle hypertrophy. Champaign, IL: Versa Press.
Legge, A. (2020, January 25). Concurrent Training: The Right Way to Combine Cardio and Strength Training. Retrieved from legionathletics: https://legionathletics.com/concurrent-training/
Haun, C., & Roberts, B. (2018, February 14). Concurrent Training for the Powerlifter, Part 2: Physiology & Application. Retrieved from strongerbyscience: https://www.strongerbyscience.com/concurrent-training-part-2/
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