Integration of different modes of exercise in relation to training goals should be taken into consideration before prescribing a total conditioning program. Different blends of exercise training modes can either enhance or hurt gains of specific fitness-related adaptations. There is potential for competing systems to interfere with fitness improvements during concurrent training. Possible explanations for non-compatibility include genetic ceiling, problems when an activity requires recruitment of similar muscle fiber types, changes in cardiovascular, immune, neuroendocrine systems that support skeletal muscle, conflicts in cellular adaptation in skeletal muscle, overreaching or overtraining, and conflicts related to support needs for systems to recover (Baechle & Earle, 2008; Fleck & Kraemer, 2014). The exercise professional should weigh the benefits and “risks” from any combination of modes performed in a given period of time, such as in or offseason, during the same week, in the same session with attention to order and exercise selection and recovery. Additionally, consideration should be given to the population; trained vs. novice, nonclinical vs. clinical, for example.
Endurance training is enhanced by strength training
In general, one can say the intense aerobic training will negatively affect strength and anaerobic performance, but strength training will generally have a positive effect on aerobic performance (Baechle & Earle, 2008; Fleck & Kraemer, 2014). Concurrent strength training and high-intensity endurance training will negatively impact or blunt power development performance (Baechle & Earle, 2008; Fleck & Kraemer, 2014). However, this may be nuanced with different training parameters and populations.
Many novice exercises will perform resistance training (RT) during the same session as an aerobic training (AT) session. For the novice, training at a higher frequency may be detrimental in regards to muscular strength gains performance (Fleck & Kraemer, 2014). Subjects who trained aerobically four days a week and resistance-trained three days per week had increases in aerobic fitness but compromised strength. This changed when frequency and intensity was decreased (Fleck & Kraemer, 2014). When novices trained 3 days per week performing AT and RT in the same session they were found to have the same strength gains as persons who trained only with strength activities alone (Fleck & Kraemer, 2014). Similar findings were seen with 2 days of RT and AT on different days (4 days per week). However, this may not be the case when comparing 2 days per week of both ST and AT on the same day with 4 days with RT and AT on separate days. In this case, the 4-day a week program was found to be superior in strength gains (Baechle & Earle, 2008).
In general power and rate of force development is negatively affected by concurrent training (Baechle & Earle, 2008; Fleck & Kraemer, 2014). Some data suggest that individuals with some endurance training experience before starting RT may not encounter problems with strength development (Baechle & Earle, 2008; Fleck & Kraemer, 2014). If this is true, then maybe the first interventions for some populations should be establishing an aerobic base. Having said that, it seems that volume and frequency are important considerations for the novice. Engaging in moderate training three days per week and allowing for adequate recovery may provide the stimulus for improving strength and endurance during the initial stages of the exercise program (Baechle & Earle, 2008; Fleck & Kraemer, 2014). For middle-age and older adults training as little as two days a week using AT and RT in the same session may produce beneficial gains in both strength and function irrespective of sequence (Fleck & Kraemer, 2014; Wilhelm et al., 2014).
Finally, other data suggest ordering the strength program first or training different muscle groups during RT that are used for AT if they are performed during the same session before RT may help (Kravitz, 2004). Interestingly, a 2012 meta-analysis found that the mode of AT was associated with an impact on strength and power gains, with running but not cycling being detrimental (Wilson et al., 2012). Additionally, the study found negative relationships between frequency and duration of endurance training for hypertrophy, strength, and power (Wilson et al., 2012). High intensity AT with concurrent RT must be planned carefully in an untrained population to avoid interference and overtraining. Many athletes must perform concurrent endurance and strength activities due to the demands of the sport. For the athlete, prior aerobic conditioning may allow for strength gains with concurrent training. However, this may not carry over to gains in power development. The data is difficult to interpret from athletes as gains made from training are usually small to begin with and many of the studies are of short duration (Fleck & Kraemer, 2014). None the less, the data suggests that higher intensity – higher volume concurrent training has a detrimental impact on strength, power and hypertrophy performance (Baechle & Earle, 2008; Fleck & Kraemer, 2014). Like novice populations, when intensity/volume is lower, interference in muscular fitness is not observed. For example, an elite soccer player who engaged in high-intensity endurance training with low-frequency RT at maximum loads were able to demonstrate improvements in strength and anaerobic performance (Fleck & Kraemer, 2014).
Endurance is generally improved by strength training. Studies done across multiple modes and program designs have demonstrated improved V02 max and aerobic power, a shift in muscle fiber types favoring oxidative capacity (type IIx to type IIa), greater tendon stiffness, improved economy of movement, and protection against injury (Baechle & Earle, 2008; Fleck & Kraemer, 2014).
Stretching routines may affect performance
It has been demonstrated that static stretch directly prior, may reduce the ability to sprint. Other data indicate that static stretching reduces the ability to perform drop jumps and explosive concentric motor actions, whereas proprioceptive neuromuscular facilitation (PNF) did not (Fleck & Kraemer, 2014). Static stretching may have time-limited benefits in regards to strength and power performance. Within 10 minutes of stretching no benefit was found in upper-body power performance of field event throwers (Fleck & Kraemer, 2014). Considering this it has been suggested that dynamic stretching warm-up is better suited for warm-up prior to power events (Fleck & Kraemer, 2014). In regards to whether chronic stretching interferes with training, it appears that no specific stretching is detrimental to strength and power development unless placed before the activity (Fleck & Kraemer, 2014).
Recommendations to reduce the likelihood of problems with concurrent training include (“Concurrent Training,” n.d.; Fleck & Kraemer, 2014):
- Monitor progressions and capacities
- Reduced training volume, and well-planned periodization techniques
- Using non-running forms of aerobic training
- Stress quality over quantity
- Reduce RT training volume when other demands for a sport take precedence
- Don’t perform RT for musculature using the same muscle groups for AT if done on the same day
- Use upper body RT when lower body sports conditioning drill are being done on the same day
- Allow for one day of complete rest each week for recovery
Baechle, T. R., & Earle, R. W. (2008). Essentials of strength training and conditioning (3th ed.). Champaign, IL: Human Kinetics.
Concurrent training. (n.d.). Retrieved February 22, 2018, from http://www.exrx.net/ExInfo/ConcurrentTraining.html
Fleck, S. J., & Kraemer, W. J. (2014). Designing resistance training programs. Champaign, IL: Human Kinetics.
Kravitz, L. (2004, May 10). The effect of concurrent training. Retrieved from https://www.unm.edu/~lkravitz/Article%20folder/concurrent.html
Wilhelm, E. N., Rech, A., Minozzo, F., Botton, C. E., Radaelli, R., Teixeira, B. C., . . . Pinto, R. S. (2014). Concurrent strength and endurance training exercise sequence does not affect neuromuscular adaptations in older men. Experimental Gerontology, 60, 207-214. doi:10.1016/j.exger.2014.11.007
Wilson, J. M., Marin, P. J., Rhea, M. R., Wilson, S. M., Loenneke, J. P., & Anderson, J. C. (2012). Concurrent Training. Journal of Strength and Conditioning Research, 26(8), 2293-2307.