The principle of training has a basic fundamental philosophy, which is to state that the body will adapt to the stresses it is consistently placed under. This refers to overload, one of the four principles of strength training. This basic principle of overload is replicate able in regards to cardiovascular and strength gains. To improve our cardiac function in exercise, our body must increase its ability to pump more blood with each heart beat(cardiac output which is the product of heart rate and stroke volume) and/or its ability to extract more oxygen from the blood to the working tissues(A-Vo2 difference). Stressing our cardiac system on a regular basis with endurance training guidelines of large muscle groups (i.e., running, biking, swimming, rowing, etc) being contracted repetitively at an intensity of 50% – 85% of Max VO2 (Powers and Howley, 2012). This type of training that stresses the heart helps increase the cardiac contractility strength while decreasing the peripheral resistance, thus improving a persons cardiovascular performance.
During longer bouts of endurance training, the body’s stress response to maintain homeostasis creates physiological adaptations to promote a steady state of exercise over a shorter span of time. Meaning, the body’s ability to maintain a more normal state of cardiorespiratory fitness is achieved at a faster pace with continued stress. Some of the physiological adaptations our body goes through are its ability to shift from the fast twitch fiber that is more prone to fatigue, over to a slow twitch fiber, which has a denser capillary capacity to improve muscle contraction for longer periods of time. A second physiological adaptation results in the increase of mitochondrial density in muscle fibers which provides the muscle a longer response to muscular contraction by increasing the amount of Adenosine Diphosphate in the cell (Powers and Howley, 2012).
Comparing endurance training against a more intense, shorter duration of resistance training, the adaptation that signals the stress response in the body is carried out in the messenger RNA that signals what type of amino acid sequence. This specific type of protein that is activated will be necessary to determine which type of muscle fiber is used for a specific style of exercise. As the exercise moves toward a higher intensity and shorter duration contraction, the stress response of the muscle fiber is to increase its synthesis of contractile proteins and induce muscular hypertrophy.
With two separate physiological adaptations that occur under two different stresses placed on the body, controversial data exists to determine if one method of training interferes with a the other. Studies have shown that including a resistance training program can add to endurance events through necessary high output occurrences that may be involved in competition. Two studies supported this view were by Baumann et al, 2012, which studied the benefit of adding resistance training that included female athletes training in the phosphagen and glycolytic energy phase, helped the regeneration of ATP production that was shown to help the female runners during times of needing a burst of energy. A similar result by Hansen et al, 2012, used hip flexion strength training for male cyclists to improve the upward stroke of the cycling motion to its subjects. Hansen’s results were that the group that performed resistance training exercises in addition to the endurance training, improved pedaling efficacy during a 5 minute sprint that finished out a 185 minute cycling phase. Most recently, a study in 2014 by Hussein et, tested subjects for rowing performance based on endurance only, concurrent mode(resistance and endurance), and resistance only. These groups were measured for increased stem cells, VO2 max, and performance over an 8 week program. The group that was involved in concurrent method of training, recorded record levels of stem cells, improved Vo2 levels and improved performance on their 2000 meter row. Evidence supports the question that strength training helps improve cardiovascular performance in events that require intermittent levels of force production.
In contrast, there seems be even a larger scope of controversy in regards to whether endurance training limits the benefits of strength gains in concurrent exercise bouts. Powers and Howley (2012) provide reasons to believe it does. Neural factors which are believed to reduce the amount of motor units activated during force production, which limits muscular strength. Performing endurance activities can lessen the amount of glycogen storage in the muscle that would be available for resistance training, which can impair the outcome of force production. The possibility of overtraining is introduced with concurrent methods of training, if both styles are met with optimal intensity over time. And lastly, a bout of endurance training can limit the ability of protein synthesis that would exist following a resistance training bout (Powers and Howley, 2012).
Powers, S., & Howley, E.. (2012). Exercise Physiology: Theory and Application to Fitness and Performance. (8th ed.). New York, NY: McGraw-Hill Companies, Inc.
ABDELSALAM, H., ELLOUZY, M., & GABER, M. (2014). EFFECT OF CONCURRENT TRAINING ON CD34+/CD45 STEM CELLS, VO2 MAX, CERTAIN PHYSICAL VARIABLES AND RECORD LEVEL OF 2000M ROWING. Ovidius University Annals, Series Physical Education & Sport/Science, Movement & Health, 14(1), 78-84.
Baumann, C. W., Rupp, J. C., Ingalls, C. P., & Doyle, J. (2012). Anaerobic Work Capacity’s Contribution to 5-km-Race Performance in Female Runners. International Journal Of Sports Physiology & Performance, 7(2), 170-174.
Hansen, Ernst A., Rennestad, Bent R., Vegge, Geir, Raastad, Truls. Cyclist’ Improvement of Pedaling Efficacy and Performance After Heavy Strength Training. 2012. International Journal of Sports Physiology and Performance, 7, 313-321.