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Kenny Guex, Chantal Daucourt and Stéphane Borloz

Context:

In the field of sport rehabilitation, an easy, valid, and reliable assessment of maximal strength is crucial for efficient muscle rehabilitation. Classically, it is performed on fitness equipment that is not necessary available in the field. Thera-Band has developed elastic bands with different resistances depending on the color of the band and on the percentage of its stretch. This may allow testing maximal strength.

Objective:

To determine validity and reliability of maximal-strength assessment of knee flexors and extensors using elastic bands.

Design:

Reliability and validity study.

Participants:

22 healthy participants (31.3 ± 7.0 y, 175.5 ± 8.5 cm, 70.7 ± 12.9 kg).

Intervention:

Participants performed 2 maximal-strength assessments, separated by 7 d, of the knee flexors and extensors using elastic bands. After the 2nd trial, a maximal concentric isokinetic test at 60°/s was performed.

Main Outcome Measures:

Correlations between 1-repetition maximum using elastic bands and peak torque on an isokinetic dynamometer were used to determine the validity of the proposed method, while ICC, CV, and SEM were used to determine reliability between the 1st and 2nd trials.

Results:

The validity of the proposed method was found to be very high (r = .93 for both knee flexors and extensors). The relative reliability was found to be very high (ICC = .98 and .99 for knee flexors and extensors, respectively), while absolute reliability was also very satisfying (CV = 3.44% and 2.33%; SEM = 1.70 and 2.16 kg for knee flexors and extensors, respectively).

Conclusions:

Thera-Band is a valid and reliable alternative to the use of fitness equipment to test maximal strength of the knee flexors and extensors in healthy subjects. The ease of use, accessibility, and low cost of elastic bands should allow regular assessment during the rehabilitation process.

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Kenny Guex, Francois Fourchet, Heiko Loepelt and Gregoire P. Millet

Context:

A passive knee-extension test has been shown to be a reliable method of assessing hamstring tightness, but this method does not take into account the potential effect of gravity on the tested leg.

Objective:

To compare an original passive knee-extension test with 2 adapted methods including gravity’s effect on the lower leg.

Design:

Repeated measures.

Setting:

Laboratory.

Participants:

20 young track and field athletes (16.6 ± 1.6 y, 177.6 ± 9.2 cm, 75.9 ± 24.8 kg).

Intervention:

Each subject was tested in a randomized order with 3 different methods: In the original one (M1), passive knee angle was measured with a standard force of 68.7 N (7 kg) applied proximal to the lateral malleolus. The second (M2) and third (M3) methods took into account the relative lower-leg weight (measured respectively by handheld dynamometer and anthropometrical table) to individualize the force applied to assess passive knee angle.

Main Outcome Measures:

Passive knee angles measured with video-analysis software.

Results:

No difference in mean individualized applied force was found between M2 and M3, so the authors assessed passive knee angle only with M2. The mean knee angle was different between M1 and M2 (68.8 ± 12.4 vs 73.1 ± 10.6, P < .001). Knee angles in M1 and M2 were correlated (r = .93, P < .001).

Conclusions:

Differences in knee angle were found between the original passive knee-extension test and a method with gravity correction. M2 is an improved version of the original method (M1) since it minimizes the effect of gravity. Therefore, we recommend using it rather than M1.

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Francis Degache, Jean-Benoît Morin, Lukas Oehen, Kenny Guex, Guido Giardini, Federico Schena, Guillaume Y. Millet and Grégoire P. Millet

The aim of study was to examine the effects of the world’s most challenging mountain ultramarathon (Tor des Géants [TdG]) on running mechanics. Mechanical measurements were undertaken in male runners (n = 16) and a control group (n = 8) before (PRE), during (MID), and after (POST) the TdG. Contact (t c) and aerial (t a) times, step frequency (f), and running velocity (v) were sampled. Spring-mass parameters of peak vertical ground-reaction force (F max), vertical downward displacement of the center of mass (Δz), leg-length change (ΔL), and vertical (k vert) and leg (k leg) stiffness were computed. Significant decreases were observed in runners between PRE and MID for t a (P < .001), F max (P < .001), Δz (P < .05), and k leg (P < .01). In contrast, f significantly increased (P < .05) between PRE and MID-TdG. No further changes were observed at POST for any of those variables, with the exception of k leg, which went back to PRE. During the TdG, experienced runners modified their running pattern and spring-mass behavior mainly during the first half. The current results suggest that these mechanical changes aim at minimizing the pain occurring in lower limbs mainly during the eccentric phases. One cannot rule out that this switch to a “safer” technique may also aim to anticipate further damages.