Measurement of the maximum knee extension velocity.

(A, B) Experimental setup for measurement. The patient was seated on an elevated bed with a wireless gyro-sensor, where they extended their knee joint five times as quickly as possible from 90°(A) to 160°(B) to hit the soft cushion. (C) The gyro-sensor. (D) Representative data of knee extension velocity. The red arrow indicates the maximum knee extension velocity of five times.</p

Correlations between gait function and knee function (n = 186).

Correlations between gait function and knee function (n = 186).</p

Changes in gait and knee function over time (n = 186).

Changes in gait and knee function over time (n = 186).</p

Multiple linear regression analysis for maximum gait speed and TUG.

Multiple linear regression analysis for maximum gait speed and TUG.</p

S1 Dataset -

(XLSX)</p

Experimental setup for measuring the quadriceps muscle strength.

Experimental setup for measuring the quadriceps muscle strength.</p

Preoperative characteristics of the patients.

Preoperative characteristics of the patients.</p

Significant increase in myoglobin protein after 5% APP feeding.

<p>Plantaris muscles from control and 5%-APP diet groups (after 8-wk feeding) were analyzed for myoglobin by ECL-western blotting referenced with α-tubulin as an internal standard (upper panel; 4 representative samples from each group). Myoglobin-band intensity was quantified by densitometry and expressed as relative units to the control (lower panel). Data bars present the mean ± SE for nine rats in each group fed with control (open bar) or the 5%-APP diet (closed bar) and a significant difference from control mean at <i>P</i> < 0.05 is indicated by (*).</p

Improvement of Endurance Based on Muscle Fiber-Type Composition by Treatment with Dietary Apple Polyphenols in Rats

<div><p>A recent study demonstrated a positive effect of apple polyphenol (APP) intake on muscle endurance of young-adult animals. While an enhancement of lipid metabolism may be responsible, in part, for the improvement, the contributing mechanisms still need clarification. Here we show that an 8-week intake of 5% (w/w) APP in the diet, up-regulates two features related to fiber type: the ratio of myosin heavy chain (MyHC) type IIx/IIb and myoglobin protein expression in plantaris muscle of 9-week-old male Fischer F344 rats compared to pair-fed controls (<i>P</i> < 0.05). Results were demonstrated by our SDS-PAGE system specialized for MyHC isoform separation and western blotting of whole muscles. Animal-growth profiles (food intake, body-weight gain, and internal-organ weights) did not differ between the control and 5% APP-fed animals (<i>n</i> = 9/group). Findings may account for the increase in fatigue resistance of lower hind limb muscles, as evidenced by a slower decline in the maximum isometric planter-flexion torque generated by a 100-s train of electrical stimulation of the tibial nerve. Additionally, the fatigue resistance was lower after 8 weeks of a 0.5% APP diet than after 5% APP, supporting an APP-dose dependency of the shift in fiber-type composition. Therefore, the present study highlights a promising contribution of dietary APP intake to increasing endurance based on fiber-type composition in rat muscle. Results may help in developing a novel strategy for application in animal sciences, and human sports and age-related health sciences.</p></div

Improvement of muscle endurance by 5% APP feeding.

<p>Maximum isometric planter-flexion force torque was measured under anesthesia after 8-wk feeding of the control or 5%-APP diet, according to Iwata et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134303#pone.0134303.ref021" target="_blank">21</a>] with some modifications. Schematic configuration of equipment is shown in panel A, in which strain gauges are attached to the footplate and connected to an instrumentation amplifier, a MacLab/4S digital converter, and a PowerMacintosh computer. A hook-shaped electrode connected to an electronic-stimulator module generated a stimulus train (250 Hz: pulse width 1 ms, duration 160 ms with intervals of 3 ms) delivered to the right tibial nerve branch that innervates calf muscles of the lower hind limb, including plantaris and gastrocnemius muscles. The amplitude (60V) was optimized as the supramaximal voltage by a separate voltage-dependency experiment using 3 control rats in which tetanic forces generated at the first electrical stimulus (at 0-s) were measured in a dose-range of 40–100 V (panel C inset). Tetanic-contraction forces measured were converted to torque (mN · m) by multiplying by the length (L) between the medial malleolus and the head of the first metatarsal bone (Mt₁); the initial value at the first stimulation (at 0-s) and the time-course change in response to 100-s successive stimulation (expressed relative to the initial value) are shown in panels B and C, respectively. Data points and bars depict the mean ± SE for nine rats in each group fed with control (open circle and bar) or the 5%-APP diet (closed circle and bar) and significant differences from control at <i>P</i> < 0.05 and <i>P</i> < 0.01 are indicated by (*) and (**), respectively. NS, no significant difference.</p