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Naser Nawayseh and Saleh AlBaiti

In recent years, whole-body vibration (WBV) training has received an increasing interest in the sports and medical fields. However, there has been inconsistency among several studies regarding the effect of WBV training on the human body, which is partly due to the lack of the existence of guidelines for using WBV training machines. To understand the effect of WBV training on the human body and build the needed regulations, it is essential first to understand the biodynamic responses to vibration which represent how vibration is transmitted to and through the human body. The purpose of this study is to systematically review previous studies that measured biodynamic responses when using WBV training machines to highlight inconsistencies in their results and provide possible reasons for them. An extensive literature search was performed on the SCOPUS database to obtain relevant studies. One hundred and fifty-six potentially relevant studies were obtained but after further screening, 23 papers from 2007 to 2020 met inclusion criteria and were included in the study. The papers were analysed with respect to acceleration, transmissibility, interface force, and apparent mass during different vibration settings, body posture, age, and sex. Results and conflicts among studies were highlighted and possible explanations for the inconsistency were provided.

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Xiu Hu, Shaojun Lyu, Min Mao, Jianwei Zhang, Wei Sun, Cui Zhang, and Qipeng Song

The team developed the newly compiled eight methods and five steps of Tai Chi (EMFSTC), which includes introductory routines to Tai Chi characterized by simple structures. This study examined the effectiveness of EMFSTC practice on balance control. A total of 31 participants were randomly assigned to EMFSTC (n = 15, age = 66.4 ± 1.7 years, received 16-week EMFSTC practice) or control (n = 16, age = 66.7 ± 1.8 years, received no practice) groups. Significant group by training interactions were observed. After EMFSTC practice, balance control improved, as indicated by decreased root mean square and mean velocity of center of pressure, proprioception threshold during knee extension, and plantar tactile sensitivity threshold at the arch. EMFSCT can be an effective rehabilitation modality to improve balance control among older adults.

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Valters Abolins and Mark L. Latash

We present a review on the phenomenon of unintentional finger action seen when other fingers of the hand act intentionally. This phenomenon (enslaving) has been viewed as a consequence of both peripheral (e.g., connective tissue links and multifinger muscles) and neural (e.g., projections of corticospinal pathways) factors. Recent studies have shown relatively large and fast drifts in enslaving toward higher magnitudes, which are not perceived by subjects. These and other results emphasize the defining role of neural factors in enslaving. We analyze enslaving within the framework of the theory of motor control with spatial referent coordinates. This analysis suggests that unintentional finger force changes result from drifts of referent coordinates, possibly reflecting the spread of cortical excitation.

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Ty B. Palmer, Jarrod Blinch, Ahalee C. Farrow, Chinonye C. Agu-Udemba, and Ethan A. Mitchell

This study aimed to examine the acute effects of fast-paced walking on isometric peak torque and rate of torque development (RTD) in regular exercising and inactive older women. Ten regular exercising (67 ± 4 years) and 10 inactive (68 ± 4 years) older women performed three isometric knee extension contractions before and after a control condition (quiet resting) and an experimental condition of fast-paced walking for 6 min. Peak torque and early (RTD100), late (RTD200), and maximum (peak RTD) RTD measurements were obtained from each contraction. Results showed no significant changes in peak torque, peak RTD, or RTD200 after walking for either group (p > .050). A significant decrease in RTD100 was observed after walking for the inactive group (p = .005) but not for the regular exercisers (p = .909). These findings highlight the importance of physical activity and suggest that a task as simple as walking may impair the rapid strength capacities of inactive older women.

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Rosiane Jesus do Nascimento, Valter Cordeiro Barbosa Filho, Cassiano Ricardo Rech, Rafaela Batista Brasil, Renato Campos Junior, Inês Amanda Streit, and Ewertton de Souza Bezerra

The current study aimed to follow the effects of social/physical distancing strategies on health-related daily physical activity and quality of life among older adults during the COVID-19 pandemic. Seventy-two older adults who were enrolled in a University–Community program in March 2020 (age = 66.8 ± 4.82 years, ♀59) answered five phone-based surveys up to 120 days after the COVID-19 outbreak (from April to August 2020). The Short Form 6D and international physical activity (short version) questionnaires were applied. A significant reduction was observed in daily physical activity levels, metabolic equivalent of task, and health-related quality of life scores as well as an increase in sitting time during the week and on weekend days (all p < .01). The authors noted differences in lifestyle conditions at the beginning of the social/physical distancing in the community assessed (p < .01). Health vulnerabilities among older adults have been emphasized during the COVID-19 outbreak, impacting daily physical activity and health-related quality of life.

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Neda Nasrollahi, Jordan Quensell, and Liana Machado

Despite an abundance of evidence that exercise benefits cognition and mood, physical activity levels among older adults remain low, with time and inaccessibility posing major barriers. Interval stair climbing is an accessible time-efficient form of physical activity demonstrated to benefit cognition and mood in young adults, but effectiveness in older adults remains unknown. To address this, 28 older adults (M age = 69.78 years, 16 females) undertook cognitive and mood assessments twice, 1 week apart, once preceded by interval stair climbing. A fairly large, albeit only marginally significant, effect size (ηp2=.12) indicated improved cognition following the moderate- to high-intensity intervention; however, rather than improving mood, older adults reported feeling more tired (g = 0.51). These outcomes provide initial indications that this mode of exercise that can easily translate to naturalistic settings offers promise as an intervention strategy, but more research is needed to optimize the protocol to suit aged populations (ACTRN1261900169014).

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Lucas Eduardo Rodrigues Santos, André dos Santos Costa, Eduardo Caldas Costa, Vinicius Oliveira Damasceno, Zhaojing Chen, Izaildo Alves de Oliveira, Karla Kristine Dames, Flávio Oliveira Pires, and Tony Meireles Santos

The purpose of the study was to investigate the effects of passive recovery with self-selected time on affect, ratings of perceived exertion, and heart rate in self-selected interval exercises (SSIE). Fifteen older women (68.1 ± 3.8 years), weekly practitioners of functional activities participated in three SSIE with self-selected recovery time (SSRT) and one self-selected continuous exercise session, all at 24 min approximately. The SSIE had the following configurations: 1′/SSRT, 1.5′/SSRT, and 2′/SSRT. The results showed that at the beginning of stimulus heart rate in 1.5′/SSRT (107.9 ± 16.5) and 2′/SSRT (114.6 ± 17.1) were significantly greater (p < .05) compared with self-selected continuous exercise (102.8 ± 14.5). The ratings of perceived exertion in self-selected continuous exercise (2.4 ± 0.4; p < .05) were higher compared with SSIE in recovery. No significant differences were found in affect. The SSIE provided similar responses based on recoveries manipulations.

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Luiz Fernado Biazus-Sehn, Rafael Reimann Baptista, Régis Gemerasca Mestriner, Bianca Pacheco Loss, Daniela Aldabe, and Felipe de Souza Stigger

Real-world walking requires shifting attention from different cognitive demands to adapt gait. This study aims to evaluate the effect of dual tasking on spatiotemporal gait parameters of older adults. Participants were asked to perform a primary complex single-walking task, consisting of a fast-paced linear and a curved gait. Primary task was performed separately and simultaneously with different motor and cognitive secondary tasks. Spatiotemporal gait parameters, walk ratio, and walk stability ratio were measured. Apart from stride length, which stood relatively unchanged, gait speed and cadence were strongly affected by cognitive dual tasking. Cadence seems to be the most impacted by dual tasking during curved gait as it combines challenges of both primary and secondary tasks. Also, during curved phase, walking ratio was significantly lower and stability ratio was greater demonstrating that participants adopted a cautious gait where maintenance of stability took preference over efficiency.

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Yuta Sekine and Norikazu Hirose

Purpose: To examine differences in resistance exercise-induced hormonal responses among young athletes according to their maturity levels. Materials and Methods : A total of 12 collegiate and 32 junior high school male athletes were enrolled. The junior high school participants were divided into pre–peak height velocity (PHV) and post-PHV groups, according to their PHV ages. The salivary testosterone, cortisol, and human growth hormone levels were analyzed before (pre), immediately after (post), and at 15 minutes after performing body weight resistance exercise. Results: The testosterone levels were higher in the collegiate than in the junior high school group (P < .01) and increased after 15 minutes of exercise (P < .01). A significant decrease in the cortisol levels postexercise in the junior high school groups (P < .01) and an increase in the human growth hormone levels at 15 minutes after exercise in the post-PHV group were observed (P < .01). In the collegiate and post-PHV groups, the testosterone-to-cortisol ratio increased post and at 15 minutes after exercise (P < .01). The testosterone-to-cortisol ratio values were higher in the collegiate than in the post-PHV (at preexercise and at 15 min after [P < .01]) and pre-PHV groups (at all times [P < .01]). Conclusion: Exercise-induced acute hormonal responses to resistance exercise may depend on individuals’ maturity levels, even in those having the same age.

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Michael H. Haischer, John Krzyszkowski, Stuart Roche, and Kristof Kipp

Maximal strength is important for the performance of dynamic athletic activities, such as countermovement jumps (CMJ). Although measures of maximal strength appear related to discrete CMJ variables, such as peak ground reaction forces (GRF) and center-of-mass (COM) velocity, knowledge about the association between strength and the time series patterns during CMJ will help characterize changes that can be expected in dynamic movement with changes in maximal strength. Purpose: To investigate the associations between maximal strength and GRF and COM velocity patterns during CMJ. Methods: Nineteen female college lacrosse players performed 3 maximal-effort CMJs and isometric midthigh pull. GRF and COM velocity time series data from the CMJ were time normalized and used as inputs to principal-components analyses. Associations between isometric midthigh pull peak force and CMJ principal-component scores were investigated with a correlational analysis. Results: Isometric midthigh pull peak force was associated with several GRF and COM velocity patterns. Correlations indicated that stronger players exhibited a GRF pattern characterized by greater eccentric-phase rate of force development, greater peak GRF, and a unimodal GRF profile (P = .016). Furthermore, stronger athletes exhibited a COM velocity pattern characterized by higher velocities during the concentric phase (P = .004). Conclusions: Maximal strength is correlated to specific GRF and COM velocity patterns during CMJ in female college lacrosse athletes. Since maximal strength was not correlated with discrete CMJ variables, the patterns extracted via principal-components analyses may provide information that is more beneficial for performance coaches and researchers.