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Muscle activity in treadmills and over-ground running
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Treadmills are becoming an increasingly popular modality for which to perform cardiovascular exercise on the basis that a treadmill exerts less stress on the knee joint that running outside on concrete. Furthermore, a Japanese study conducted in 2010 by Ayako Higashihara et al. in the Journal of Sports Sciences discovered that increasing treadmill speeds – 50%, 75%, 85%, and 95% of maximum – correlated with increased hamstring activation, insinuating that running on a treadmill can cause greater hamstring adaptations than running outside.
Training at near maximum speeds causes a kinematic adaptation in one’s gait, such that increased speeds correlated with a decrease in knee flexion and a subsequent increase in hip flexion. An increase in hip flexion describes the motion of one’s knees being driven upwards to reduce the angle of the hip joint; therefore, greater hip flexion allows an athlete to exert a greater amount of force with their stride resulting in an increase in power – twhich ranslates to an increase in speed.
Moreover, it was discovered within the Higashihara study that increasing speeds, one’s hamstring will stretch more rapidly, alluding to a more forceful stride as a quicker stretch will result in a quicker contraction via Newton’s third law of motion that every action has an equal and opposite reaction.
When comparing the effectiveness of running on a treadmill as opposed to running on the ground, it is often debated as to which modality offers greater benefits with regards to increasing one’s speed. Heiner Baur et al. discovered in 2007 (Isokinetics and Exercise Science) that muscle activation occurred sooner while running on the treadmill as opposed to running over-ground; however, the muscle activation also occurred for a longer period of time while on the treadmill.
A notable difference in the electromyographic (EMG) readings was the increased activation of the peroneus longus – an ankle stabilizer – that was present within the treadmill data, insinuating that running on a treadmill requires one to exhibit a greater amount of stability such that exercising at a pre-determined speed can cause a greater amount of stress on the runner which alludes to a potential decline in one’s form. Furthermore, EMG activity observed a declination of soleus activation while running on the treadmill as the belt on the treadmill acts as a means to move the leg backwards negating the primary purpose of the soleus that is to propel the body forward.
In addition to varying leg muscle activation while on a treadmill, it is observed that in trained athletes, there is an increase in core activation as observed via EMG. Core muscles of interest in a study conducted by David Behm et al., for Applied Physiology, Nutrition, and Metabolism in 2009 were the external obliques, the lower abdominals, and the erector spinae of the lumbo-sacral region.
Behm et al. observed triathletes and non-running trained athletes on a treadmill and discovered that the triathletes exhibited more muscle activation via the core muscles than the non-running trained athletes, insinuating that an athlete that has been trained to run for long distances understands that to perform effectively, core activation is required. Furthermore, an increase in core activation is required as running on a treadmill is unstable in that the belt moves at a pre-set speed requiring the athlete to match said speed that can result in instability for said athlete while performing.
Therefore, it is insinuated that for athletes to become faster and stronger, they should train at a high percentage of maximum speed on a treadmill, as high speed treadmills train an athlete to perform with greater hip flexion, greater core activation, and quicker hamstring activation. These points of interest are valid with regards to runners such that greater hip flexion will result in a greater force exerted on the ground, greater core activation will result in an increase in stability, and quicker hamstring activation will result in quicker contractions – increased maximal strength, increased balance, and increased speed respectively that all allude to an increase in power which correlates with faster times while running.
References
Baur, H., Hirschmüller, A., Müller, S., Gollhofer, A., & Mayer, F. (2007). Muscular activity in treadmill and overground running. Isokinetics and Exercise Science, 15, 165-71.
Behm, D. G., Cappa, D., & Power, G. A. (2009). Trunk muscle activation during moderate- and high-intensity running. Applied Physiology, Nutrition, and Metabolism = Physiologie Appliquée, Nutrition Et Métabolisme, 34(6), 1008-1016. doi:http://dx.doi.org/10.1139/H09-102.
Higashihara, A., Ono, T., Kubota, J., Okuwaki, T., & Fukubayashi, T. (2010). Functional differences in the activity of the hamstring muscles with increasing running speed. Journal of Sports Sciences, 28(10), 1085-1092. doi:http://dx.doi.org/10.1080/02640414.2010.4943082.
Tyler Vindua is an intern with SoccerFitness. Soccer Fitness Inc., is a soccer-specific strength and conditioning company located in Toronto. For more information about Soccer Fitness, please visit www.soccerfitness.ca.
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