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18Elite running sport: injury risks versus footwork techniques analysis
UDC 796.012
E.S. Negodenko1, 2 S.N. Kapitanov2
Dr. Med., Professor L.V. Kapilevich1, 2
1National Research Tomsk State University, Tomsk
2National Research Tomsk Polytechnic University, Tomsk
Corresponding author: [email protected]
Abstract
Objective of the study was to analyze the key running footwork options versus the running efficiency and running related injuries exposure in the sport elite.
Research methods and structure. We tested the running footwork techniques of the cross-country running elite and found the running related injuries incidence rate in the forefoot strike groups being 2.6 times lower than in the rearfoot strike ones. We also found the group diagnosed with a chronic exercise syndrome reporting meaningful pain relief within one year after making transition to the forefoot strike technique.
We used a strike index as the key criterion in the running footwork tests and analyses. The strike index is a characteristic of the ground contact point location in percent to the full length of the sole - applicable to classify the running footwork into at least the rearfoot strike and forefoot strike techniques. It was found that the running footwork normally changes at submaximal running speed. We used a cluster analysis to group the sample into the (1) forefoot-strike-only group that never resorts to a different ground contact technique; (2) rearfoot strike-only group; and (3) transitional group that normally uses rearfoot strike making the foot flatter at higher speeds. We also found that the strike index tends to significantly sag with the running speed growth
Results and conclusion. It is commonly believed that the most efficient running technique requires the movements being kept economic due to the 'vertical stiffness' model of the lower-limb muscle work to attain a high strike index; with the running kinematics and kinetics also dependent on the running footwear. Thus the too soft shoes with cushioning soles may be detrimental to the lower-limb stiffness, in contrast to the thin-sole ones. The study shows, however, that we have good reasons to believe that the forefoot strike technique is generally less traumatic for the lower limbs than the rearfoot strike. It should also be emphasized that some special types of footwear may distort the running kinetics and kinematics and thereby increase the risks of running related injuries.
Keywords: running, running footwork, running related injuries, running footwear.
Background. Popularity of jogging and running has been on the rise for the last few decades. The sport research community has demonstrated a growing interest in causes and effects of the running related injuries albeit the efforts to reduce the running related injuries incidence rates have been mostly unsuccessful as yet [16]. Most analysts tend to believe that the running related injuries exposure is directly correlated with the running footwork i.e. foot striking/ ground contact technique [6, 12].
Objective of the study was to analyze the key running footwork options versus the running efficiency and running related injuries exposure in the sport elite.
Results and discussion.
Running footwork versus running related injuries correlation analysis
We tested the running footwork techniques of the cross-country running elite and found the running related injuries incidence rate in the forefoot strike
Theory and Practice of Physical Culture I teoriya.ru I October № 10 2021
groups being 2.6 times lower than in the rearfoot strike ones [13]. We also found the group diagnosed with a chronic exercise syndrome reporting meaningful pain relief within one year after making transition to the forefoot strike technique [7].
We used a strike index as the key criterion in the running footwork tests and analyses. The strike index is a characteristic of the ground contact point location in percent to the full length of the sole - applicable to classify the running footwork into at least the rearfoot strike and forefoot strike techniques [12]. It was found that the running footwork normally changes at sub-maximal running speeds [15]. We used a cluster analysis to group the sample into the (1) forefoot-strike-only group that never resorts to a different ground contact technique; (2) rearfoot strike-only group; and (3) transitional group that normally uses rearfoot strike making the foot flatter at higher speeds [8 ]. We also found that the strike index tends to significantly sag with the running speed growth [15, 16].
Our study confirmed benefits of the foot/ lower-limb muscles being kept stiff (commonly referred to as the 'vertical stiffness' requirement). Of special interest was our finding that the vertical stiffness should be directly correlated with the ground contact time rather than the stride frequency despite the latter is favored by the running sport communities. It was also found that soft shock-absorbing running shoes may be detrimental to the vertical stiffness - as opposed to the light firm-soled shoes that tend to facilitate the stiff footwork, reduce the ground contact time and, hence, improve efficiency of the running stride biomechanics [9, 10].
Running efficiency is an important success factor heavily dependent on the individual running biomechanics, with the rearfoot strike commonly believed more efficient although the causes and effects of the running footwork options are still being analyzed and discussed [11, 14].
Practical running footwork analysis
Despite the experimental data that shows benefits of the anterolateral ground contact for stride stiffness and shorter ground contact time, the sport community still favors the external foot contact in addition to the above most efficient option. Practical analyses showed the ground contact in the straight sprints dominated by angular foot placements, with the toe mostly turned outward. The ground contact with the outer part of the foot is followed by a full
front-foot contact with or without heal contact, depending to the actual individual speed-strength fitness - with a full plantar part contact in some cases. The analysts believe that such techniques help mitigate the strike at the beginning and develop a good support for push off by the end of the movement sequence [3].
It should be mentioned that the commercial running communities and coaching athletes promote the concept of any technique being efficient enough conditional on the body mass center being kept as close to the bent knee as possible to guarantee, as they argue, softer ground contact with no loss for the speed and low risk of injuries to ligaments and joints [1]. An ideal running footwork technique in this concept should secure fast and soft ground contact by the front foot [2].
Running footwear in the running related injuries context
Practical studies demonstrate benefits of the soft light shoes for the running efficiency in addition to the other common running efficiency factors including: shorter vertical body mass center oscillation amplitudes; sharper knee angle in the swing phase; shorter range with faster angular flexion/ extension speed of the plantar muscles at the toe push-off moment; short arm swing amplitudes; lower ground response peaks; faster shoulder rotation speeds in the transverse plane; longer angular excursion of the hips and shoulders around the polar axis in the transverse plane; accumulated elastic energy inputting efficiency, etc. The above aspects should be considered in the context of the individual anthropometrics including the preferable middle body length in the men's sprint and slightly above the middle body length in the women's sprint; high body mass index with ectomorphic or ectomesomorphic physique; low fat mass; lower-limb mass centers in the thighs; narrow pelvis and smaller-size feet; etc. [4].
Modern running shoes are designed with high cushioning and sole rest technology to secure the foot is comfortably fixed to avoid potential injuries and/or adjustments to the habitual movement patterns; albeit the sport statistics still report no reductions in the injury rates. Retrospective injury statistics of 1982-2006 when the special running footwear has been common show 79% of the sport elite reporting lower limb injuries and disorders including patellofemoral pain, iliotibial tract syndrome, plantar fasciitis, and Achilles tendonitis [5]. Some analysts
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argue that the running footwear should be specialized for the professional and amateur sports, with a high sensitivity to the foot anthropometrics. Such individual footwear will help reduce the running related injuries, offset faults in the running footwork and safety practices and, hence, contribute to the competitive progress.
Conclusion. It is commonly believed that the most efficient running technique requires the movements being kept economic due to the 'vertical stiffness' model of the lower-limb muscle work to attain a high strike index; with the running kinematics and kinetics also dependent on the running footwear. Thus the too soft shoes with cushioning soles may be detrimental to the lower-limb stiffness, in contrast to the thin-sole ones. The study shows, however, that we have good reasons to believe that the forefoot strike technique is generally less traumatic for the lower limbs than the rearfoot strike. It should also be emphasized that some special types of footwear may distort the running kinetics and kinematics and thereby increase the risks of running related injuries.
References
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