Cardio before or after strength training: what does science say?

How does cardio before or after strength training affect your results?

Whether you do cardio before or after strength training is more than a matter of habit: the decision directly affects the results of both strength and endurance training. Researchers call this phenomenon the interference effect: aerobic and strength training performed in the same workout can inhibit each other’s adaptive responses (Hickson, 1980). The traditional rule is simple: start with the type of training that serves your main goal.

A study comparing different training sequences within the same session found that strength training before cardio preserved measures of muscle strength significantly better than the reverse order (Chtara et al., 2005). A 2012 meta-analysis also showed that long (over 20 min), intense cardio sessions before strength training can reduce maximal strength by up to 10–20% (Wilson et al., 2012).

When does it make sense to do cardio before strength training?

There are specific situations where cardio before strength training is entirely appropriate:

• As a warm-up – 5–10 minutes of low-intensity cardio (walking, gentle cycling) warms up your muscles and joints, raises your body temperature and prepares your body for the training load ahead. This type of warm-up does not interfere with strength training or significantly deplete glycogen stores.
• When endurance is your goal – marathon runners, triathletes and other endurance athletes whose main goal is aerobic capacity should start with cardio because it is their training priority.
• On separate training days or with a longer gap – when cardio and strength training take place on different days or at least 6 hours apart on the same day, the interference effect largely disappears (Robineau et al., 2016). This is the best approach for most athletes.

For practical advice on combining cardio and strength training, see Should you run before strength training or lift weights before running?, which explores the same topic through specific examples.

An important warning: high-intensity interval cardio (HIIT) before strength training is particularly problematic. It depletes muscle glycogen stores and substantially reduces coordination and explosive strength, making the strength training that follows less effective.

Why should you do strength training before cardio?

If your goal is muscle size, strength or a change in body composition, both ACSM (American College of Sports Medicine) and NSCA (National Strength and Conditioning Association) recommend doing strength training before cardio (ACSM, 2009).

The reasons are clearly physiological:

1. Glycogen use – cardio depletes muscle glycogen, the main fuel for strength training. Fatigued muscles cannot generate an optimal tension–time product or recruit enough motor units.
2. Hormonal environment – strength training stimulates testosterone and growth hormone secretion. If you start with cardio, this hormonal peak has already passed by the end of the workout.
3. Neuromuscular fatigue – cardio causes central nervous system fatigue, which impairs the precision of motor control and reduces the number of fast-twitch muscle fibers that can be recruited when lifting weights.

In practice, complete all your strength and hypertrophy exercises first, then add 20–30 minutes of moderate-intensity cardio to burn fat or maintain cardiovascular fitness. According to the World Health Organization’s physical activity guidelines, adults need at least 150–300 minutes of moderate-intensity aerobic activity each week, along with muscle-strengthening exercises twice a week, so a deliberate combination of both types of training is strongly recommended.

How does nutrition support both types of training?

What you eat before and after your workout is just as important as your training sequence. A lack of protein impairs both muscle recovery after strength training and glycogen replenishment after cardio.

General nutrition recommendations for a day that combines both types of training:

• 2–3 hours before your workout: a meal rich in carbohydrates and protein (such as oatmeal with an egg) to ensure your glycogen stores are full before strength training.
• Soon after your workout (within 30–60 min): 20–40 g of high-quality protein alongside fast-absorbing carbohydrates for muscle recovery.

For more detailed guidance, see What to eat before and after a workout and What to eat before and after workouts. For inspiration from real results, see Estonian achievers before and after, where successful people share their training and nutrition habits.

References

• Hickson RC (1980). Interference of strength development by simultaneously training for strength and endurance. Eur J Appl Physiol Occup Physiol. 45(2-3):255-63. PMID: 7193134
• Chtara M, Chamari K, Chaouachi M, et al. (2005). Effects of intra-session concurrent endurance and strength training sequence on aerobic performance and capacity. Br J Sports Med. 39(8):555-60. PMID: 15793095
• Wilson JM, Marin PJ, Rhea MR, et al. (2012). Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. J Strength Cond Res. 26(8):2293-307. PMID: 22002517
• Robineau J, Babault N, Piscione J, et al. (2016). Specific training effects of concurrent aerobic and strength exercises depend on recovery duration. J Strength Cond Res. 30(3):672-83. PMID: 25486295
• American College of Sports Medicine (2009). ACSM position stand: progression models in resistance training for healthy adults. Med Sci Sports Exerc. 41(3):687-708. PMID: 19204579