Cardiovascular exercise often only falls in to a bodybuilder’s vocabulary either as a feeling of the need to strip away fat, or in reference to their avoidance. Many persons wishing to increase their muscle size avoid moderate intensity cardiovascular exercise for fear of it harming their muscular growth. Alternately bodybuilders often perceive cardiovascular exercise as a necessity to strip away fat, spending long hours doing low intensity exercise to burn calories. But what if everything you knew about cardiovascular exercise is wrong...
Most people likely categorise cardiovascular exercise based on the modality (e.g. cycling, swimming, running, etc.) and/or the purpose of performing that exercise (improving/retaining cardiovascular fitness, burning calories, etc.). This conviction has been supported by the exercise science community for decades. But of course science progresses, and often things we think we knew to be true turn out to be false. The earth, after all, is not flat. So what if I told you that to improve cardiovascular fitness you could lift weights, and to improve muscle mass you could perform cardiovascular exercise. Well here’s the evidence that supports exactly that hypothesis.
Resistance exercise improves cardiovascular performance...
A recent paper by Dr. James Steele, et al. (1) reviewed the research surrounding resistance exercise and cardiovascular fitness and concluded that training to a point of momentary muscular failure facilitates the same acute physiological responses and chronic physiological adaptations to performing cardiovascular exercise. The authors clarify that this doesn’t suggest that a person performing resistance exercise can optimise their cardiovascular fitness for say running or cycling, partly as a result of the skill acquisition of running or cycling, etc. But rather that resistance exercise appears to catalyse similar physiological adaptations.
Whilst this appears to represent a challenge to current thinking, some of the evidence supporting this hypothesis has existed for some time. For example previous research supports that exercise at an intensity of effort above lactate threshold improves cardiovascular fitness to a greater degree than training at a lower intensity of effort (2, 3). Resistance exercise is almost always performed at an intensity of effort above lactate threshold, and indeed the perception that resistance exercise might enhance cardiovascular exercise is becoming more common. We might however, ask the question as to whether the opposite is true; can traditional cardiovascular exercise produce physiological adaptations similar to that of resistance exercise.
Cardiovascular exercise increases muscle size...
As intensity of effort increases in a task there is a sequential recruitment of muscle fibres, this is referred to as the size principle. The smallest muscle fibres are recruited first and the larger and more forceful muscle fibres, which fatigue the quickest and recover the slowest, are recruited last (e.g. 4, 5). As a result it is often suggested that resistance exercise should be performed to the highest intensity of effort; e.g. momentary muscular failure, to stimulate the most muscle fibres, and as such catalyse the greatest response in strength (6) and muscle size (7).
But what if you performed cycling instead of resistance exercise? A research paper by Lundberg, et al. (8) compared persons training one leg with resistance exercise only, and the other leg with resistance exercise and a cycle task. [It is noteworthy that the authors referred to the cycle task as aerobic exercise, where aerobic is a reference to the exercise intensity being low enough that the body could produce energy through aerobic metabolism.] The cycle task consisted of pedalling at 70% of maximal power (70%Wmax) at a cadence of 60rpm for 40 minutes after which the workload was increased in ~20W increments and participants cycled until failure. It is this increase in intensity of effort that is important to the present hypothesis. That the participants cycled until failure suggests that the exercise had ceased to be aerobic. [The authors might have made reference to the cycle task as being aerobic as a product of the historical thinking that a prolonged cycle task is, for the most part, aerobic.]
What is more interesting than the analysis of the methodology is that muscle hypertrophy of the quadriceps was greater in the group that did resistance exercise and the cycle task (14%) compared to the group that performed resistance exercise only (8%). The authors comment “Although we acknowledge these collective findings remain controversial, it may be that low-force actions repeated until failure ultimately promote muscle hypertrophy”. In fact, previous research has suggested that increases in muscle hypertrophy are comparable irrespective of using heavy or light loads when resistance exercise is performed to muscular failure (4, 9, 10, 11). As such it does not appear controversial that the study by Lundberg, et al. reported significant increases in muscle size as a result of repeated low-force contractions to muscular failure, it actually supports the previous research.
Since cardiovascular exercise at this intensity appears to build muscle and certainly catalyses a higher metabolic response during and after exercise, it is also logical that cardiovascular exercise at a higher intensity of effort will help in improving body composition. Long hours spent walking on a treadmill to strip away fat might be a thing of the past and soon replaced by brief high intensity cycle sessions.
Very recently Knopka and Harber (12) published a review of this area and Fisher, et al. (13) presented this hypothesis in more detail in a peer-reviewed scientific journal article. Certainly this challenges previous thinking but in practicality bodybuilders or persons wishing to increase their muscular size should not avoid cardiovascular exercise for fear of harming their potential muscle size gains, they should merely perform the exercise at an intensity that supports the growth of muscle by training at a high intensity of effort.
If you want to look further then anecdotal evidence is everywhere in elite sports performed to failure; take a look at the quadriceps of track cyclists (e.g. Robert Förstemann, Rene Enders, Maximillian Levy, Chris Hoy, etc.)!! Of course the current evidence is primarily supportive of non-impact exercise modalities such as cycling but future research might support this hypothesis with alternate modalities of cardiovascular exercise.
- Steele J, Fisher J, McGuff D, Bruce-Low S, Smith D. Resistance Training to Momentary Muscular Failure Improves Cardiovascular Fitness in Humans: A Review of Acute Physiological responses and Chronic Adaptations. J Exerc Phys, 2012; 15: 53-80
- Henritze J, Weltman A, Schurrer RL, Barlow K. Effects of training at and above the lactate threshold on the lactate threshold and maximal oxygen uptake. Eur J Appl Physiol, 1985; 54: 84-88
- Weltman A, Seip RL, Snead D, Weltman JY, Haskvitz EM, Evans WS, Veldhuis JD, Rogol AD. Exercise Training at and above the Lactate Threshold in Previously Untrained Women. Int J Sports Med, 1992; 13: 257-263
- Carpinelli R. The Size Principle and a Critical Analysis of the Unsubstantiated Heavier-is-better Recommendation for Resistance Training. J Exerc Sci Fit, 2008; 6: 67-86
- Jungblut S. The correct interpretation of the size principle and its practical application to resistance training. Med Sport, 2009; 13: 203-209
- Fisher J, Steele J, Bruce-Low S, Smith D. Evidence-Based Resistance Training Recommendations. Med Sport, 2011; 15: 147-162
- Fisher J, Steele J, Smith D. Evidence-Based Resistance Training Recommendations for Muscular Hypertrophy. Med Sport, 2013; 17: 217-235
- Lundberg TR, Fernandez-Gonzalo R, Gustafsson T, Tesch PA. Aerobic exercise does not compromise muscle hypertrophy response to short-term resistance training. J Appl Physiol, 2013; 114: 81-89
- Mitchell CJ, Churchward-Venne TA, West DW, Burd NA, Breen L, Baker SK, Phillips SM. Resistance exercise load does not determine training-mediated hypertrophic gains in young men. J Appl Physiol, 2012; 113: 71-77
- Ogasawara R, Loenneke JP, Thiebaud RS, et al. Low-load bench press training to fatigue results in muscle hypertrophy similar to high-load bench press training. Int J Clin Med, 2013; 4: 114-21.
- Van Roie E, Delecluse C, Coudyzer W, et al. Strength training at high versus low external resistance in older adults: Effects on muscle volume, muscle strength, and force-velocity characteristics. Exp Gerontol, 2013; 48(11): 1351-1361
- Konopka AR, Harber MP. Skeletal muscle hypertrophy after aerobic exercise training. Exerc Sport Sci Rev 2014; 42: 53-61
- Fisher J, Steele J. Questioning the Resistance/aerobic Dichotomy: If they work hard enough, what muscles don’t know will only make them stronger... and bigger... and more aerobic! J Human Kinetic 2014; IN PRESS