Can phase angle from bioelectrical impedance analysis associate with neuromuscular properties of the knee extensors?

Abstract

Maintenance and improvement of neuromuscular functions is crucial for everyone regardless of age. An easy way to assess neuromuscular properties without muscle contraction is useful especially for those who cannot perform strenuous muscular force production, such as older adults and patients with orthopedic or cognitive disorders. Bioelectrical impedance analysis (BIA) can assess body electrical properties e.g., phase angle (PhA) which is regarded as muscle quantity/quality index. The purpose of this study was to investigate associations of PhA with neuromuscular properties of the knee extensors in 55 young (n = 23) and older (n = 32) adults. The values of PhA of the right thigh and whole-body were determined with BIA at 50 kHz. The participants performed 4-s maximal voluntary isometric contraction (MVIC) to measure peak torque (PTMVIC), and 1-s brief MVIC to assess rate of torque development (RTD) over the time interval of 0–200 ms. As markers of physiological mechanisms of muscle force production, twitch contractile properties (peak twitch torque, rate of twitch torque development, and time-to-peak twitch torque) of the knee extensors obtained by femoral nerve electrical stimulation, and muscle activity assessed as root mean square values of electromyographic activity (EMG-RMS) during PTMVIC and RTD measurements were measured. Thigh and whole-body PhA significantly correlated with PTMVIC (r ≥ 0.555, p < 0.001) and electrically evoked twitch parameters (peak twitch torque, rate of twitch torque development, and time-to-peak twitch torque; |r| ≥ 0.420, p ≤ 0.001), but not RTD (r ≤ 0.237, p ≥ 0.081) or EMG-RMSs (|r| ≤ 0.214, p ≥ 0.117). Stepwise multiple linear regression analysis revealed that thigh PhA was selected as a significant variable to predict PTMVIC but not RTD. Whole-body PhA was not selected as a significant variable to predict PTMVIC or RTD. In conclusion, both thigh and whole-body PhA can associate with maximal voluntary muscle strength of the knee extensors, and this association may be due to intrinsic contractile properties but not neural aspects. Regarding prediction of the knee extensor strength, thigh PhA is preferable as the predictor rather than whole-body PhA which is used as a widely acknowledged indicator of sarcopenia.

Relation of leg phase angle from bioelectrical impedance analysis with voluntary and evoked contractile properties of the plantar flexors

“…The leg phase angle was significantly associated with the twitch contractile properties of the plantar flexors (Figure 1). This supports the findings of a previous study (Hirata et al, 2022b), which elucidated the correlations between the thigh phase angle and twitch contractile properties of the knee extensors. Phase angle is a function of inverse of resistance.…”

“…This implies that the assessment of muscle function using segmental phase angle is more detectable for plantar flexors than for knee extensors. Although a previous study (Hirata et al, 2022b) reported that the thigh phase angle did not correlate with rapid force generation or neuromuscular activity in knee extensors, these associations might be masked because of the relatively low percentage volume of knee extensors in the thigh compared with that of plantar flexors. Phase angle possibly relates to rapid force generation and neuromuscular activity because of the following reports: Yamada et al (2017) reported that the phase angle evaluated from the lower extremities correlated with maximal power during a counter-movement jump, which is a multi-joint-level explosive strength.…”

“…Since the phase angle is well known to correlate with maximal muscle strength (Sacco et al, 2021;Akamatsu et al, 2022), one of the underlying mechanisms of the association between phase angle and exercise performance is the relationship between phase angle and maximal muscle strength. However, to the best of our knowledge, only one previous study has investigated the relationship of phase angle with rapid force generation ability, intrinsic contractile property, and neuromuscular activity at a single-joint level (Hirata et al, 2022b). This previous study reported that the phase angle derived from BIA correlated with electrically evoked twitch contractile properties (peak twitch torque [PT twitch ], rate of twitch torque development [RTD twitch ], and time-topeak twitch torque [TPT twitch ]) but not the rate of torque development (RTD; an index of rapid force generation ability) during maximal voluntary isometric contraction (MVIC) or electromyographic (EMG) activity in the knee extensors.…”

“…Although the phase angle is often measured at the whole-body level, particularly in studies on sarcopenia, it can also be measured at the segmental level. When estimating the function of a certain muscle group with the phase angle, it is better to measure the phase angle for a body segment that contains the target muscle group than for the whole body or other segments (Yamada et al, 2021;Hirata et al, 2022b;Bongiovanni et al, 2022). Because a body segment contains several muscle groups such as agonists, synergists, antagonists, phase angle measured for a certain body segment cannot assess function of only a target muscle group.…”

Surface Electromyography-Driven Parameters for Representing Muscle Mass and Strength

“…BIA has evolved over the past years to become a practical method to provide reliable parameters of low muscle mass, which has been incorporated into the recent diagnostic criteria of sarcopenia [ 2 ]. As variables obtained from BIA are also found to be associated with muscle function, BIA has become a promising tool for skeletal muscle evaluation [ 11 ].…”