The Magnitude of Inter-limb Asymmetry and Its Assocation with Inter-limb Asymmetry in Distance Runners and Non-runners

Lower Limb Functional Asymmetry in Healthy Novice, Moderately and Highly-trained Distance Runners Versus Non-athletes

Distance running is one of the most popular and most accessible ways to engage in physical activity. Although distance running offers numerous health-related benefits and protects against noncommunicable diseases (e.g., type 2 diabetic, obesity, hypertension), research has indicated a high prevalence of running-related injuries with a more pronounced incidence among novice runners (i.e., 17.8 injuries per 1000h) compared to their highly trained peers (i.e., 7.2 injuries per 1000h).

Interlimb asymmetry has previously been related to higher injury risk as well as to impaired sports performances. Nevertheless, to date, research on the degree and evolution of functional asymmetry (e.g., unequal strength between limbs) in distance runners is scarce and the role of functional asymmetries in running performance and running-related injuries remains unclear. Moreover, and despite the great number of unilateral tests available in the literature, there currently exists no reliable and run-specific field-based test battery to examine the degree of lower limb asymmetry in distance runners. Therefore, this study aims to assess the test-retest, intra- and inter-rater reliability of a newly created running-specific field-based test battery to assess the presence and degree of functional lower limb asymmetry among novice, moderatly and highly trained distance runners as well as a control group of non-athletes. The second objective is to assess the association between inter-limb asymmetry and running performance.

Inclusion Criteria:

• • Being aged between 20 and 50 years at Tfamiliarization

  • Being free from any medical attention injury (i.e., injury that results in a participant receiving medical attention) for at least 6 months upon Tfamiliarization
  • Speaking Dutch, French or English

• Highly trained distance runners:

  • Running at least 150km per month for at least 3 months

Moderately-trained runners:

• Running between 40 - 150 km per month for at least 6 months

  - Novice distance runners:

• Running not more than 10km per week for the past 12 months

  - Control group of non-athletes

• Performing <75min of systematic moderate to vigorous-intensity physical activity per week and having no experience in systematic (un)structured running activities for the past 5 years

Exclusion Criteria:

• • Being younger than 20 years or older than 50 years at Tfamiliarization

  • Any known relevant medical history or current condition (e.g., neurological diseases, inner ear diseases) that could affect the performance of the functional tests (e.g., balance in repeated hop tests)
  • Participants that have undergone a surgery at lower limb level during the past 6 months
  • Medication or drug use (e.g., blood pressure medicines)that could affect the performance of the functional tests (e.g., balance in repeated hop tests)
  • Participants performing more than two hours per week of unilateral sports (e.g., tennis or soccer)