Introduction
It’s a question that confuses many devotees of strength training who watch their heart rate climb during weightlifting: if my heart rate is hitting the aerobic zone for a large portion of my workout, do I really need to do cardio at all?
It’s not uncommon during compound lifts – exercises such as squats, deadlifts, lunges, chest presses, and hip thrusts – for heart rate levels to climb to 150 beats per minute and even beyond. That’s well into the aerobic zone, and sometimes weightlifters’ heart rates can even hit anaerobic levels during strength training.
World Health Organization Guidelines
The World Health Organization (WHO) recommends that individuals get a minimum of 150 minutes of moderate-intensity aerobic exercise a week, or 75 minutes of vigorous exercise. The question arises: does strength training that raises your heart rates to these levels qualify to be added to this tally?
Aerobic Fitness and Strength Training
According to Emmanuel Stamatakis, professor of physical activity, lifestyle, and population health at the University of Sydney’s faculty of medicine, the answer depends somewhat on your base level of fitness. "The bottom line is the lower the baseline aerobic fitness level, the higher the relative benefit to the heart of resistance training," says Professor Stamatakis. "The basic principle is that someone who has a low level of aerobic fitness, and they initiate strength training, they should expect an increase in aerobic fitness through resistance training."
Baseline Fitness and Improvement
For individuals with a low level of aerobic fitness, starting strength training can lead to significant improvements in aerobic fitness. However, those who already engage in a fair amount of cardio and add strength training to their routine might see negligible improvement in aerobic fitness from strength training alone. For these individuals, especially younger or early middle-aged people, strength training alone may not provide sufficient protection for long-term heart outcomes.
Strength Training and Mortality
Recent research, including a study published by Professor Stamatakis in the American Journal of Epidemiology, provides good news about strength training. The study found that strength training is associated with substantial reductions in all-cause mortality and cancer mortality. The research indicated that participation in any form of strength training, whether bodyweight training or using weights in the gym, was linked with a 23% reduction in all-cause mortality and a 31% reduction in cancer mortality .
Strength Training Benefits
Strength training has been shown to lower circulating levels of sex hormones, reducing the risks of breast and endometrial cancer in women and prostate cancer in men. The study concluded that, in terms of mortality risk reduction, adherence to strength training guidelines (at least twice a week) appears to be at least as important as adherence to aerobic exercise guidelines .
Cardio Exercise and Cardiovascular Health
However, the research also highlighted that only those who participated in cardio exercise achieved a lower risk of cardiovascular disease. Cardio specifically trains the heart and lungs to perform more efficiently, which is crucial for cardiovascular health.
Combined Benefits of Strength and Cardio Training
Studies consistently show that performing both strength and cardio training side-by-side confers the biggest health benefits, including reducing the risk of cardiovascular disease and mortality. High-Intensity Interval Training (HIIT) or CrossFit classes that incorporate weights can achieve both strength and cardio goals effectively .
Practical Recommendations
For avid weightlifters reluctant to engage in traditional cardio, a brisk 20-minute walk once a day can almost meet the required minimum level of aerobic activity. Alternatively, participating in two 40-minute HIIT training classes per week can also suffice.
Including cardio in a weekly workout plan is essential for cardiovascular fitness and protection from heart disease. Strength training offers significant benefits, including reductions in mortality and cancer risk, but for comprehensive health benefits, a combination of both cardio and strength training is recommended.
References
- Stamatakis, E., et al. (2018). "Associations of specific types of sports and exercise with all-cause and cause-specific mortality: a cohort study of 80,306 British adults." *British Journal of Sports Medicine*, 52(10), 682-688.
- Stamatakis, E., et al. (2017). "Does strength-promoting exercise confer unique health benefits? A pooled analysis of data on 11 population cohorts with all-cause, cancer, and cardiovascular mortality endpoints." *American Journal of Epidemiology*, 187(5), 1102-1112.
- Dankel, S. J., et al. (2016). "The Effects of Muscle Strength Training on Cardiovascular Disease Risk Factors." *Sports Medicine*, 46(3), 311-328.
- Schjerve, I. E., et al. (2008). "Both aerobic endurance and strength training programmes improve cardiovascular health in obese adults." *Clinical Science*, 115(9), 283-293.
- Weston, M., et al. (2014). "Effects of low-volume high-intensity interval training (HIT) on fitness in adults: a meta-analysis of controlled and non-controlled trials." *Sports Medicine*, 44(7), 1005-1017.