Influence of exercise intensity on training-induced tendon mechanical properties changes in older individuals.
This study compared the effects of low vs. high intensity training on tendon properties in an elderly population. Participants were pair-matched (gender, habitual physical activity, anthropometrics, and baseline knee extension strength) and then randomly assigned to low (LowR, i.e., ~40 % 1RM) or high (High R, i.e., ~80 % 1RM) intensity resistance training programmes for 12 weeks, 3× per week (LowR, n = 9, age 74 ± 5 years; HighR, n = 8, age 68 ± 6 years). Patellar tendon properties (stiffness [K], Young's modulus [YM], cross-sectional area [T CSA], and tendon length [T L]) were measured pre and post training using a combination of magnetic resonance imaging (MRI), B-mode ultrasonography, dynamometry, electromyography and ramped isometric knee extensions. With training K showed no significant change in the LowR group while it incremented by 57.7 % in the HighR group (p < 0.05). The 51.1 % group difference was significant (p < 0.05). These differences were still apparent when the data was normalized for T CSA and T L, i.e., significant increase in YM post-intervention in HighR (p < 0.05), but no change in LowR. These findings suggest that when prescribing exercise for a mixed genders elderly population, exercise intensities of ≤40 % 1RM may not be sufficient to affect tendon properties.
CNRS UMR 7338, Biomécanique et Bioingénierie, Université de Technologie de Compiègne, 60205, Compiègne cedex, France, jgrosset@utc.fr.
Jean-Francois
JF
Grosset
Leigh
L
Breen
Claire E
CE
Stewart
Katherine E
KE
Burgess
Gladys L
GL
Onambélé
D000368:Aged; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D053581:Muscle Strength Dynamometer; D010809:Physical Fitness / Q000502:physiology*; D013710:Tendons / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography