Effects of walking training at different speeds on body composition, muscle contractility, and immunocytes in the elderly: A single-blinded randomized controlled trial

BACKGROUND

This study investigated the changes in body composition, muscle contractility and immunocytes of the elderly using three types of walking.

MATERIAL AND METHODS

Seventy-six participants were randomly assigned to control group (CON), slow walking group (SWG), moderate walking group (MWG), or fast walking group (FWG).

RESULTS

Muscle mass in CON decreased (-2.55 ± 3.63%; P < 0.05), while it increased in FWG (1.92 ± 4.46%; P < 0.05). Fat mass in CON increased, whereas it decreased in MWG and FWG (-18.71 ± 14.22%; P < 0.001). Tc (contraction time) of biceps femoris (BF) decreased in CON, while a decreasing tendency was seen in SWG. Although Tc of BF increased in MWG, it showed a marked increase in FWG (21.19 ± 24.53%; P < 0.05). A similar tendency was observed in the rectus femoris. Leukocytes did not change in CON, but they showed an increasing tendency in MWG and FWG. Neutrophils decreased in CON, whereas the other groups showed an increasing tendency. Lymphocytes (10.25 ± 19.48%; P < 0.01) and helper T cells (14.32 ± 17.99%; P < 0.05) showed an increase in FWG, and NK cell was improved in SWG, but showed a clear increase in MWG (38.45 ± 96.96%; P < 0.05) and FWG (52.69 ± 58.37%; P < 0.05).

CONCLUSIONS

This study concludes that fast walking by the elderly improves the muscle contractility, which can also be expected to improve the function of immunocytes by increased or maintained muscle mass and decreased fat mass after 12 weeks.

Moderate- to fast-walking improves immunocytes through a positive change of muscle contractility in old women: a pilot study

This study aimed to examine whether compared with a program without walking, intervention programs with three types of walking can improve the muscle property and immunocytes in elderly women. Thirty-two subjects were randomly assigned to control group (CON), slow walking group (SWG), moderate walking group (MWG), and fast walking group (FWG). Three types of walking on treadmill were 30 min a day, 5 days/wk for 12 weeks. Muscle contraction time (Tc), maximum displacement (Dm), and immunocytes were tested by tensiomyography and flow cytometry. After the intervention, FWG had an increasing tendency in the muscle mass compared with other three groups. Tc of biceps femoris (BF) decreased in CON and SWG, while Tc of BF in MWG and FWG (30.58%±23.71%) increased. It was similar in the rectus femoris (RF). Although Dm of BF and RF increased in CON and SWG, those decreased in MWG and FWG. Leucocytes of CON and SWG had a decreasing tendency, those of MWG (9.65%±13.01%) and FWG (13.01%± 13.58%) increased. In the neutrophil, only CON decreased, whereas the three groups showed an increasing tendency. Helper T cell was increased only in FWG (19.61%±19.94%), showing significant differences between groups (P=0.009, η ²=0.378). Natural killer cell was improved in SWG and MWG but showed a clear increase in FWG (75.76%±63.57%). It might be confirmed that walking for elderly increases the muscle property of the lower legs as they walk faster, which might be expected to improve the immunocytes function.

Two-dimensional spatial error distribution of key tensiomyographic parameters

Tensiomyography detects the contraction time (Tc) and amplitude (Dm) of muscle belly thickening during maximal isometric twitch contraction. The assessment of both parameters is highly reliable; however, it seems that their calculation depends on the measurement point. The aim of the study was to determine spatial relative error distribution of Tc and/or Dm within a two-dimensional array of 27 (3 × 9) measurement points in comparison to the reference point (RP) in 12 male participants (22.5 ± 3.1 years). The RPs were determined as follows: in the biceps brachii (BB) at 50% of the humerus length; in the erector spinae (ES) at the height of the iliac crest; in the vastus lateralis (VL), vastus medalis (VM), and rectus femoris (RF) at 30%, 20%, and 50% of femur length above the patella, respectively. The surface area under the 3% relative error in Dm (BB: 4.0; VL: 3.8; VM; 8.2; RF: 6.2; ES: 2.4 cm²) was lower than in Tc (BB: 6.9; VL: 3.8; VM; 4.6; RF: 9.5; ES: 3.7 cm²), yielding merged values (BB: 3.9; VL: 3.7; VM; 4.8; RF: 5.1; ES: 2.4 cm²). Dm show twice as steep relative error rate when moving away from the RP in comparison to Tc, which seems to be less sensitive to spatial sensor positioning.

Neural, biomechanical, and physiological factors involved in sex-related differences in the maximal rate of isometric torque development

Objective

Recent research has reported that lower maximal rate of torque development (dτ/dt_max) exhibited by females, relative to males, during knee extension can be accounted for by normalization to a maximal voluntary contraction (MVC); however, this was not seen in the upper limb.

Purpose

The aim of the current work was to examine the contribution of maximum strength (τ_max), twitch contraction time (CT), muscle fiber condition velocity (MFCV), and rate of muscle activation (Q₃₀) to sex-differences in the dτ/dt_max during maximal isometric dorsiflexion.

Methods

Thirty-eight participants (20 males; 18 females) performed both maximal voluntary and evoked isometric contractions of the tibialis anterior across 3 days. Ten maximal compound muscle action potentials were elicited and subsequently followed by three, 5-s contractions. From the recordings, MFCV, dτ/dt_max, τ_max, CT, electromechanical delay (EMD), root-mean squared (RMS) amplitude, peak-to-peak voltage (Vpp), and Q₃₀ were calculated.

Results

An ANCOVA showed that τ_max accounted for all the sex-differences in dτ/dt_max (p = 0.96). There were no significant differences between groups with respect to MFCV, RMS amplitude, Vpp amplitude, or CT. However, there was a significant sex-difference in dτ/dt_max, τ_max, and Q₃₀. Females had longer evoked EMD times compared with males (15.69 ± 10.57 ms versus 9.95 ± 3.46 ms; p = 0.01), but the voluntary EMD times were not different.

Conclusion

The current research supports the work by Hannah et al. Exp Physiol 97:618–629, (2012) that normalization to MVC in the quadriceps is able to account for all sex-differences in rate of toque development in the lower limb.