The Simultaneous Development of Strength and Aerobic Capacity; Exploring Concurrent Training.
The term “Concurrent Training” is the label that has been associated training protocols concerned with the simultaneous development of strength and aerobic fitness[1-6]. From a coaching perspective, athletes in most major sports probably undergo or will benefit from a concurrent training protocol, as the demands of many sports tend to require a degree of both strength and endurance. Taking Rugby, for example, players have to have the muscle mass, strength and power, to make hits, take hits, participate in scrums etc. But also must be able to maintain a relative intensity of play over 80 minutes. Boxers need to deliver powerful punches and engage in short high-intensity clashes, but also need to have the aerobic capacity to potentially last 12-15 rounds. Naturally, we should be interested in how to optimise our training programs to best prepare our athletes for the vast array of demands they may experience within their respective sports.
Academic interest in concurrent training began in the 80’s, with the flagship study conducted by Hickson (1980). Hickson trained three groups of untrained individuals for a period of 10 weeks. His cohorts were; a strength development group, an endurance group and a concurrent training group, who performed the training protocols of the other two groups simultaneously. The results were interesting. As expected the strength group got stronger and the endurance group fitter. The concurrent training group, however, saw non-significant differences in performance increase with respect to the endurance group, but did see significantly stunted strength development. This phenomenon associated with concurrent training has been called the “interference effect”[1,3].
The exact mechanisms for the interference effect are not yet fully understood, Hickson himself suggested it could have simply been the result of the greater overall training volume causing the participants to overreach. While more current evidence suggests issues such as the conflicting regulation of mTOR and AMPK enzymatic pathways (both of which are acutely up-regulated after strength and endurance training respectively) could also be a contributing factor. Either way, the relevance of this “interference effect” is not to be understated. As we mentioned before a significant amount of athletes across a wide array of sports should be (or are currently) undertaking some kind of concurrent training protocol, and being aware of such physiological responses to concurrent training is vital to ensure optimal athlete development as well as preventing overtraining or injury.
The interference effect also suggests that concurrent programs will have to be designed “in their own way”, meaning that from a physiological and training load perspective, the coach must first consider a concurrent program at the macroscopic level. Taking into consideration the array of stressors the athlete will be exposed to throughout the training program and how they will, in turn, influence the acute performance and chronic adaptive capacity of the individual athletes. More simply, it’s very unlikely that if we were to take a specific running protocol and a specific lifting protocol, and “mash them together” that the combined program would produce optimal results, as neither individual protocol was designed with consideration for the other.
There have been different proposals on how to best manage the interference effect, but personally, I give preference to the concurrent training model outlined by Docherty & Sporer (2000). This model derives itself from block periodization theory. Broadly speaking, the fundamental principle of block periodization is that training stimuli are essentially separated and organised into specific mesocycles (referred to as “training blocks”), which are then sequenced in a fashion where the adaptations gained from Block A, increase the potential for adaptation in block B, etc. In sport, the overall macrocycle will essentially be a sequence of different training blocks that lead to a peak for maximal sport performance at a specific moment in time. I tend to visualise block periodization in the shape of a pyramid, starting with a base block, and building through to an inevitable peaking block.
The fundamental reasoning behind Docherty and Sporer’s model begins with dividing training adaptations into two separate subcategories; “central” and “peripheral”, the term “Peripheral adaptation” tends to refer to adaptations that will occur within the working muscles themselves (i.e., hypertrophy, increase in mitochondrial density or metabolic enzyme content)
In endurance training the term “central adaptation” generally refers to development within the heart and cardiovascular system (i.e. hypertrophy of the left ventricle, or an increase in stroke volume) Whereas, in strength training central adaptation tends to refer to more specific development of the central nervous system with respect to increasing the efficiency of skeletal muscle.
The model then structures itself by shifting focus to developing training blocks that will never emphasise concurrently developing peripheral adaptations in both strength and endurance at the same point in time. Essentially, for any given block of training, the periphery will only predominantly receive either a strength, or endurance training stimulus, but never both at the same time.
The given rationale for doing this is that by essentially ensuring that training stimuli are kept constantly on polar ends of the spectrum, they’ll be less overall “competition” within the working muscle, and that this may help to significantly minimise the interference effect.
García-Pallarés et al. (2009) conducted a 12-week concurrent training study on 11 elite level kayakers, using this model as the basis for the development of their training program. The study reported concurrent increases in both strength measurements (1rm bench press, 1rm bench pull) and aerobic power at three separate testing sessions throughout the study. While this obviously can’t suggest total validation of the model’s efficacy, it does lend to the idea that to some extent, this polarisation of stimuli does actually work.
And it’s that final point which is why personally, I really like this model. In order to explain why, first let me take a brief aside. There is some debate whether coaches should emphasise using a block model (as outlined previously) or alternative methods of program design such as daily undulating periodization (DUP) which tends to a higher level of stimulus variance. DUP usually consists rotating between developing strength, power and hypertrophy throughout the training microcycle, instead of giving each a dedicated mesocycle like a more block focused model would. Which brings me back to my point of why I think Docherty and Sporer’s model, provides a good principle approach for developing concurrent training protocols, the principle of application of polarizing stimulus can be just as easily applied in a DUP model as it could be in a block periodization model, training stimuli can still be coupled appropriately within individual training sessions and training sessions that may cause acute interference with one another can be polarized to opposite sides of the training microcycle.
Whether this would lead to the same effectiveness found in the block model presented by García and Pallarés, has to the best of my knowledge, not been formally investigated. Which means, there is definitely a need for further research on this topic, but personally, I feel the polarisation of training stress is the true underlying principle here, thus we would potentially see similar results, using different periodization protocols.
My closing thoughts will relate to the underlying theme of this article and tie in with the theme of my article. A guiding principle of our programming process should always be the consideration of the total stress we apply to the athlete. Every rep in a set and every mile on the road should be questioned, not only in terms of its individual necessity to the adaptive goal, but also in terms of how it will interact with the overall system of the athlete and their personal wellness.
1. Docherty, D. & Sporer, B. A proposed model for examining the interference phenomenon between concurrent aerobic and strength training. Sports Med. 30, 385–394 (2000).
2. García-Pallarés, J., Sánchez-Medina, L., Carrasco, L., Díaz, A. & Izquierdo, M. Endurance and neuromuscular changes in world-class level kayakers during a periodized training cycle. Eur. J. Appl. Physiol. 106, 629–638 (2009).
3. García-Pallars, J. & Izquierdo, M. Strategies to optimize concurrent training of strength and aerobic fitness for rowing and canoeing. Sport. Med. 41, 329–343 (2011).
4. Hickson, R. C. Interference of Strength Developement by Simultaneously Trining for Strength and Endurance. Eur. J. Appl. Physiol. 263, 255–263 (2000).
5. James, L. P., Kelly, V. G. & Beckman, E. M. Periodization for Mixed Martial Arts. Strength Cond. J. 35, 34–45 (2013).
6. Schaun, M. I. et al. The effects of periodized concurrent and aerobic training on oxidative stress parameters, endothelial function and immune response in sedentary male individuals of middle age. Cell Biochem. Funct. 29, 534–542 (2011).
7. Nader, G. A. Concurrent strength and endurance training: From molecules to man. Med. Sci. Sports Exerc. 38, 1965–1970 (2006).