Effects of the Type of Exercise Training on Bone Health Parameters in Adolescent Girls: A Systematic Review.

Interventional studies offer strong evidence for exercise's osteogenic impact on bone particularly during growth. With rising osteoporosis rates in older women, enhancing bone strength early in life is crucial. Thus, investigating the osteogenic effects of different types of physical activities in young females is crucial. Despite varied findings, only two systematic reviews tried to explore this topic without examining how different types of exercise may affect bone health in adolescent girls. The first aim of this systematic review was to assess the impact of exercise training on bone health parameters in adolescent girls, and the second aim was to investigate whether the type of exercise training can modulate this effect. A systematic literature search was conducted using common electronic databases from inception - January 2023. Seven studies (355 participants) were eligible for inclusion in this systematic review. Two studies dealt with resistance training, 3 studies applied plyometric training, 1 study used team sports, and 1 study used dancing. Results indicate that plyometric training increases lumbar spine bone mass in adolescent girls. Well-designed randomized controlled trials with a proper training period (> 12 weeks) are needed to advocate a specific type of training which has the highest osteogenic effect.

Acute effects of sodium citrate supplementation on competitive performance and lactate level of elite fitness challenge athletes: A crossover, placebo-controlled, double-blind study.

Purpose: The performance of sodium citrate has been investigated in high-intensity exercises, but fewer studies have addressed the role of citrate in weight-bearing exercises. Methods: Twenty fitness challenge athletes, aged 24-32 years, volunteered to participate in this crossover, placebo-controlled, double-blind study. Initially, ten athletes were given a placebo and asked to complete a fitness challenge (i.e., chin-ups, squat jumps, dips, walking lunges, sit-ups, and burpees-devil press). Another ten athletes were supplemented with sodium citrate 0.5 g/kg body mass supplements 3 h prior to performing the fitness challenges. The same procedures were completed two days later with the supplement and placebo dextrose groups switched in a cross-over design. Athletes and assessors were blinded for the experimental condition (placebo vs. verum). Lactate levels were measured 5 min after exercise. The athletes' performance on each item of the fitness challenge as well as their lactate levels, were compared. Differences between the means of the measured variables were contrasted using a dependent t-test. Results: Supplementing sodium citrate substantially improved athletes' performance in all six fitness challenge items (p < 0.05, 0.69

The Duration of Non-Local Muscle Fatigue Effects.

Non-local muscle fatigue (NLMF) refers to a transient decline in the functioning of a non-exercised muscle following the fatigue of a different muscle group. Most studies examining NLMF conducted post-tests immediately after the fatiguing protocols, leaving the duration of these effects uncertain. The aim of this study was to investigate the duration of NLMF (1-, 3-, and 5-minutes). In this randomized crossover study, 17 recreationally trained participants (four females) were tested for the acute effects of unilateral knee extensor (KE) muscle fatigue on the contralateral homologous muscle strength, and activation. Each of the four sessions included testing at either 1-, 3-, or 5-minutes post-test, as well as a control condition for non-dominant KE peak force, instantaneous strength (force produced within the first 100-ms), and vastus lateralis and biceps femoris electromyography (EMG). The dominant KE fatigue intervention protocol involved two sets of 100-seconds maximal voluntary isometric contractions (MVIC) separated by 1-minute of rest. Non-dominant KE MVIC forces showed moderate and small magnitude reductions at 1-min (p < 0.0001, d = 0.72) and 3-min (p = 0.005, d = 0.30) post-test respectively. The KE MVIC instantaneous strength revealed large magnitude, significant reductions between 1-min (p = 0.021, d = 1.33), and 3-min (p = 0.041, d = 1.13) compared with the control. In addition, EMG data revealed large magnitude increases with the 1-minute versus control condition (p = 0.03, d = 1.10). In summary, impairments of the non-exercised leg were apparent up to 3-minutes post-exercise with no significant deficits at 5-minutes. Recovery duration plays a crucial role in the manifestation of NLMF.

Effects of wearing fixed orthodontic appliance on dynamic balance, reaction time, and pain perception in adolescents and young adult elite athletes.

OBJECTIVE: To investigate the effects of using fixed orthodontic appliance on dynamic balance, auditory/visual reaction times, as well as pain perception in adolescent and young adult elite athletes. METHODS: A total of 34 elite athletes (n = 19 males) aged 16-21 years from different sports (track and field sprint, long jump and discus throw) were randomly allocated to treatment (n = 17) or control (n = 17) groups. The treatment group received self-ligating brackets with 0.04 cm super-elastic nickel-titanium arch wire, placed in the brackets to correct the teeth position. Perceived pain (i.e., visual analogue scale), dynamic balance (i.e., Y balance test), and auditory reaction time and visual reaction time using Direct RT software were assessed before (day-1), and on five occasions after fixed orthodontic appliance placement (day+1, +3, +7, +14, and +30). The two groups' quantitative data [expressed as mean (standard deviation)] for each occasion were compared using the Student's t-test. Comparisons of the Y-balance test, auditory reaction time, visual reaction time, and pain visual analogue scale data were each made between the 6 occasions via a factorial A × B analysis of variance in order to check for the possible interaction between the two groups and the (6) consecutive days (occasions). RESULTS: Compared to the control group, the treatment group showed significantly (i) lower values of anterior reach for both the dominant ([78(4) vs. 75(3)%, respectively]) and the non-dominant [76(3) vs. 74(4)%, respectively] legs at day+3, and (ii) higher values of pain visual analogue scale at day+1, day+3, and day+7 [0.00(0.00) vs. 4.94(1.25); 0.00(0.00) vs. 4.12(1.17), and 0.00(0.00) vs. 0.41(0.51), respectively). Factorial analysis of variance revealed that only pain visual analogue scale values were different between the two groups at day+1 and day+3. CONCLUSION: FOA induced a high pain level during the first week following its placement in elite athletes.

Corticospinal excitability and reflex modulation in a contralateral non-stretched muscle following unilateral stretching.

PURPOSE: Muscle stretching effect on the range of motion (ROM) and force deficit in non-stretched muscle, and the underlying mechanisms, is an ongoing issue. This study aimed to investigate crossover stretching effects and mechanisms on the plantar flexor muscles. METHODS: Fourteen recreationally active females (n = 5) and males (n = 9) performed six sets of 45-s static stretching (SS) (15-s recovery) to the point of discomfort of the dominant leg (DL) plantar flexors or control (345-s rest). Participants were tested for a single 5-s pre- and post-test maximal voluntary isometric contraction (MVIC) with each plantar flexor muscle and were tested for DL and non-DL ROM. They were tested pre- and post-test (immediate, 10-s, 30-s) for the Hoffman (H)-reflex and motor-evoked potentials (MEP) from transcranial magnetic stimulation in the contralateral, non-stretched muscle. RESULTS: Both the DL and non-DL-MVIC force had large magnitude, significant (↓10.87%, p = 0.027, pƞ2 = 0.4) and non-significant (↓9.53%, p = 0.15, pƞ2 = 0.19) decreases respectively with SS. The SS also significantly improved the DL (6.5%, p < 0.001) and non-DL (5.35%, p = 0.002) ROM. The non-DL MEP/MMax and HMax/MMax ratio did not change significantly. CONCLUSION: Prolonged static stretching improved the stretched muscle's ROM. However, the stretched limb's force was negatively affected following the stretching protocol. The ROM improvement and large magnitude force impairment (statistically non-significant) were transferred to the contralateral muscles. The lack of significant changes in spinal and corticospinal excitability confirms that the afferent excitability of the spinal motoneurons and corticospinal excitability may not play a substantial role in non-local muscle's ROM or force output responses.

Effects of Kinesio Taping on Tuck Jump Performance in Competitive Male Athletes.

This study aimed to measure the acute effects of kinesio taping at different stretches on tuck jump performance in active individuals. Seventy-five males (23.01±2.24 years, 178.35±8.12 cm, 72.47±6.58 kg) were randomly distributed into three groups: (1) kinesio taping without stretch, (2) kinesio taping with approximately 50% stretch, and (3) kinesio taping with approximately 75% stretch. The tuck jump performance of all participants was determined at baseline, immediately after applying kinesio taping, and 24 and 72 hours later. The participants' tuck jump performance did not improve immediately after the kinesio taping application, 24 hours, and 72 hours after the application. No significant differences were found between the kinesio taping groups at any time point (p>0.05). This study demonstrated no effects of kinesio taping on neuromuscular performance.

The Impact of Sport-discipline and Sex on Physical Fitness and Bone Markers in Athletes.

This study was performed to determine the impact of sex and sport-discipline on physical fitness and bone markers in young sub-elite track and field athletes. One hundred and forty-four track and field sub-elite athletes (78 males aged 17.8±1.6 years; 66 females aged 17.2±1.9 years) volunteered to participate in this study and were categorized according to their disciplines in endurance (EG: n=67) or power athletes (PG: n=77). A significant main effect of sex was observed for C-telopeptide type I collagen (CTx) (F=11.37; p<0.001; η2=0.10, moderate), for osteocalcin (OC) (F=8.58; p<0.004; η2=0.09, moderate) and for N-terminal propeptide of procollagen type I (PINP) (F=7.96; p<0.05; η2=0.07, moderate). The average CTx, OC and P1NP levels were significantly higher in males compared with females (0.05

How effective are external cues and analogies in enhancing sprint and jump performance in academy soccer players?

This study investigated the effect of external (EC) and internal coaching cues (IC), analogies with a directional component (ADC) on sprint (20 m) and vertical jump performance in academy soccer players (n = 20). A repeated-measures analysis, with post-hoc comparisons, was used to identify any differences between these cues and a neutral (control) cue. Significant differences were found for both sprint (p < 0.001) and jump (p = 0.022) comparisons among cue types. In post-hoc analyses for the 20 m sprint, significant differences were observed between the EC and the IC, favouring the EC (p < 0.01, ES = 1.27 [CI: 0.24, 2.30]), and "away" ADC and the IC, favouring the "away" ADC (p < 0.01, ES = 1.21 [CI: 0.19, 2.22]). No other cues showed significant differences. For vertical jump, there was just one significant difference between comparisons, that being for the "away" ADC vs. the neutral cue, favouring the latter (p = 0.023, ES = 0.4 [CI: -0.04 to 0.84]). It appears that ECs and ADCs are most effective when coaching sprinting performance in academy soccer players. However, simply encouraging maximal effort from a youth athlete also appears to be a reasonable cueing strategy to drive performance in youth athletes.

Association Between Foundation Strength and Weightlifting Exercises in Highly Trained Weightlifters: Support for a General Strength Component.

ABSTRACT: Zecchin, A, Puggina, EF, Hortobágyi, T, and Granacher, U. Association between foundation strength and weightlifting exercises in highly trained weightlifters: support for a general strength component. J Strength Cond Res 37(7): 1375-1381, 2023-In addition to specific weightlifting exercises (i.e., clean and jerk and snatch), foundation strength exercises (i.e., overhead press, front squat, and deadlift) constitute an integral part of the weightlifters' training regime. The unexamined concept behind this training plan is that foundation strength exercises are associated with clean and jerk and snatch performance, implying the existence of a general strength component. We thus determined the relationship between performance in foundation strength exercises (overhead press, front squat, and deadlift) and weightlifting exercises (clean and jerk and snatch) in weightlifters. Well-trained weightlifters ( N = 19, age: 26.8 ± 4.4 years; body mass index: 27.6 ± 2.3 kg·m -2 ; and training history: 4.6 ± 0.8 years) performed 1 repetition maximum tests (1RM) in foundation strength and weightlifting exercises, over 14 days, in a randomized order. We observed significant correlations in 1RM performance between the overhead press and snatch ( r = 0.69), front squat and snatch ( r = 0.73), overhead press and clean and jerk ( r = 0.67), and front squat and clean and jerk ( r = 0.72, all r values: p < 0.01). No significant correlations were found for 1RM performance between the snatch and deadlift or between the clean and jerk and deadlift ( r- range: 0.20-0.58; p > 0.05). Stepwise linear regression revealed that 1RM performance in the overhead press and front squat explained 62% of the variance in snatch 1RM performance ( F = 5.51; p < 0.04). Overhead press and front squat 1RM performance explained 59% of the variance in the clean and jerk 1RM performance ( F = 5.14; p < 0.04). Our results demonstrate the existence of a general strength component between selected foundation strength exercises and weightlifting performance. However, the use of the front squat and overhead press to increase 1RM performance in weightlifting exercises needs to be determined in future research using a different methodological approach (i.e., longitudinal protocols), given that the observed correlations do not necessarily imply causation.

Measures of Physical Fitness Improve Prediction of Kayak and Canoe Sprint Performance in Young Kayakers and Canoeists.

ABSTRACT: Gäbler, M, Prieske, O, Elferink-Gemser, MT, Hortobágyi, T, Warnke, T, and Granacher, U. Measures of physical fitness improve prediction of kayak and canoe sprint performance in young kayakers and canoeists. J Strength Cond Res 37(6): 1264-1270, 2023-Markers of talent selection and predictors of performance in canoe and kayak sprint are not yet well defined. We aimed to determine the combination of variables (i.e., demographic, anthropometric, and physical fitness) that most accurately predicts sprint performance (i.e., 500- and 2000-m race time) in semielite, young kayakers and canoeists ( n = 39, age 13 year, 10F). The level of significance was set at p < 0.05. Linear regression analyses identified boat type (i.e., kayak or canoe), skeletal muscle mass, and average power during a 2-minute bench pull test, normalized to body mass, as predictors of 2000-m race time (R 22000 m = 0.69, Akaike information criterion [AIC] = 425) and together with vertical jump height, as predictors of 500-m race time (R 2500 m = 0.87, AIC = 255). This was an improvement over models containing solely demographic variables (R 2500 m = 0.66, AIC = 293; R 22000 m = 0.44, AIC = 446) and over models containing demographic and anthropometric variables (R 2500m = 0.79, AIC = 277; R 22000 m = 0.56, AIC = 437). Race time showed the strongest semipartial correlations with the 2-minute bench pull test (0.7 ≤ r ≤ 0.9). Adding physical fitness data (i.e., 2-minute bench pull test) to demographic and anthropometric data improves the prediction accuracy of race times in young kayak and canoe athletes. The characteristics of physical fitness tests should resemble as much as possible the biomechanical (e.g., prime movers) and metabolic (e.g., duration) demands of the sport.

Key Anthropometric Variables Associated With Front-Crawl Swimming Performance in Youth Swimmers: An Allometric Approach.

ABSTRACT: Sammoud, S, Negra, Y, Chaabene, H, Bouguezzi, R, Attia, A, Granacher, U, Younes, H, and Nevill, AM. Key anthropometric variables associated with front-crawl swimming performance in youth swimmers: an allometric approach. J Strength Cond Res 37(6): 1259-1263, 2023-This study aimed to establish key anthropometric characteristics (e.g., optimal body height, limb-segment length, and girth/breadth ratios) related to 100-m front-crawl performance in young swimmers. In total, 74 swimmers (boys [ n = 41; age: 18.1 ± 3.5 years]; girls [ n = 33; age: 15.9 ± 3.1 years]) participated in this study. We adopted a multiplicative allometric log-linear regression model to identify key anthropometric characteristics associated with 100-m front-crawl swimming performance. The main outcomes indicated that length ratio = ([height/leg length]), foot length and ankle girth, biacromial breadth, and % of body fat were associated with 100-m front-crawl mean swimming speed performance. These findings highlight the importance of assessing anthropometric characteristics in young front-crawl swimmers for talent identification and development.

Long-Term Monitoring of Training Load, Force-Velocity Profile, and Performance in Elite Weightlifters: A Case Series With Two Male Olympic Athletes.

ABSTRACT: Sandau, I and Granacher, U. Long-term monitoring of training load, force-velocity profile, and performance in elite weightlifters: a case series with two male Olympic athletes. J Strength Cond Res 36(12): 3446-3455, 2022-The aim of this case series approach was to analyze weekly changes in force-velocity relationship (FvR) parameters (v̅0, F̅0, P̅max) and theoretical snatch performance (snatchth) assessed through a specific snatch pull test in preparation of the European and World Championships in 2 male elite weightlifters. A second aim was to examine associations of training load (volume, volume load, average load), barbell FvR-parameters, and snatchth over a period of 2 macrocycles in preparation of the same competitions. FvR-parameters, snatchth, training load data, and body mass were assessed weekly over 40 weeks. Using the smallest real difference approach, significant (p ≤ 0.05) decreases in v̅0 and increases in F̅0, P̅max, and snatchth were found within macrocycles. However, the large significant loss in body mass (≈11%) in athlete 1 during macrocycle 2 represents most likely a main factor for diminished P̅max, and snatchth in macrocycle 2. Based on cross-correlation analyses, barbell FvR-parameters and snatchth were significantly (p ≤ 0.05) associated with maximal strength, muscle power, and speed training load variables. Moderate correlations (0.31-0.47) were found between training load and P̅max and snatchth in athlete 2. It can be concluded that the applied training loads elicits improvements in P̅max and snatchth because the athlete approached the main competitions. However, because of the large loss in body mass, the relations between training load and barbell FvR-parameters and snatchth were less clear in athlete 1. It seems that a loss in body mass as a result of a change in bodyweight category mitigates P̅max development during the macrocycle and hindered to reach peak snatchth at the main competitions.

Validity and Reliability of a Snatch Pull Test to Model the Force-Velocity Relationship in Male Elite Weightlifters.

ABSTRACT: Sandau, I, Chaabene, H, and Granacher, U. Validity and reliability of a snatch pull test to model the force-velocity relationship in male elite weightlifters. J Strength Cond Res 36(10): 2808-2815, 2022-This study examined the concurrent validity and within-session reliability of parameters describing the force-velocity relationship (FvR) such as maximal force, velocity, power, and the theoretical one repetition maximum snatch performance ( snatchth ) during the snatch pull. The FvR was assessed using the multiple-load (FvR m ) approach and the 2-load (FvR 2 ) approach. Eight male elite weightlifters from the German national team executed the snatch pull in 2 separate experiments. For the concurrent validity assessment (experiment one), during the snatch pull, 7 loads from 70 to 100% were lifted to compute the FvR m , and 2 loads (70 and 100%) were lifted to compute the FvR 2 . For the reliability assessment (experiment 2), a test-retest protocol for the FvR 2 was conducted. Input FvR parameters were determined from video-based barbell tracking. Results indicated no differences (all p > 0.05; all d ≤ 0.07) and extremely large correlations (all r ≥ 0.91) between the FvR m and FvR 2 parameters. The within-session reliability of FvR 2 parameters was excellent (all intraclass correlation coefficient ≥0.97; SEM % ≤1.23%). The percentage smallest real difference (SRD 95 %) of FvR 2 parameters ranged between 1.89 and 3.39%. In summary, using the snatch pull to model FvR 2 parameters is a valid and reliable approach that can easily be integrated into elite weightlifters' daily training routines.

Comparison of Cross-Education and Global Training Effects in Adults and Youth After Unilateral Strength Training.

ABSTRACT: Chaouachi, A, Ben Othman, A, Chaouachi, M, Hechmi, A, Farthing, JP, Granacher, U, and Behm, DG. Comparison of cross-education and global training effects in adults and youth after unilateral strength training. J Strength Cond Res 36(8): 2121-2131, 2022-Youth strength training research examining contralateral, homologous (cross-education), and heterologous (global training) effects after unilateral training have provided mixed results and the relationship to adults has not been compared. The objective was to compare adult and youth cross-education and global training effects on dominant and nondominant limb testing. Initially, 15 men and 15 prepubertal boys volunteered for each unilateral chest press (CP), handgrip training, and control groups ( n = 89). Individuals trained their dominant limb 3 times per week for 8 weeks and had their dominant and nondominant limbs tested for CP and leg press 1 repetition maximum (1RM), handgrip, knee extension and flexion, and elbow extension and flexion maximum voluntary isometric contractions (MVICs). Adult CP training gains were significantly greater than youth with lower-body testing ( p = 0.002-0.06), whereas youth CP training gains exceeded adults with upper-body tests ( p = 0.03-0.07). Training specificity was evident with greater CP 1RM increases with CP vs. handgrip training for both youth ( p < 0.0001) and adults ( p < 0.0001). Handgrip training elicited greater gains in handgrip MVICs compared with other strength tests ( p < 0.0001). In conclusion, only contralateral CP 1RM showed a training advantage for unilateral CP over unilateral handgrip training. Adults showed greater gains with lower-body testing, whereas youth showed greater gains with upper-body testing.

Reliability and validity of a modified Illinois change-of-direction test with ball dribbling speed in young soccer players.

The purpose of this study was to assess test-retest reliability, discriminative and criterion-related validity of the modified Illinois change-of-direction (CoD) test with ball dribbling-speed (ICODT-BALL) in young soccer players of different biological maturity and playing levels. Sixty-five young male soccer players (11.4 ± 1.2 years) participated in this study. The participants were classified according to their biological maturity (pre- and circumpeak height velocity [PHV]) and playing-level (elite and amateur players). During the test-retest time period of two weeks, the following tests were performed during week one and as retest during week two: ICODT-BALL, ICODT, 4 × 9-m shuttle-run, countermovement-jump, triple-hop-test, maximum-voluntary isometric-contraction of back-extensors, Stork, Y-Balance, 10 and 30-m sprints. The ICODT-BALL showed excellent relative (r = 0.995, p < 0.001; ICC = 0.993) and absolute (SEM < 5%; SEM < SWCs(0.2, 0.6, 1.2)) reliability. The circum-PHV (22.8 ± 1.7-s) and elite (22.5 ± 0.9-s) players showed better ICODT-BALL performance than their pre-PHV (24.2 ± 2.5-s) and amateur (25.1 ± 2.8-s) counterparts (p = 0.028 and p < 0.001, respectively). The ICODT-BALL showed "very good" (AUC = 0.81) discriminant validity when comparing the elite and amateur players, and "moderate" (AUC = 0.67) discriminant validity when compared to pre-PHV and circum-PHV boys. ICODT-BALL demonstrated "large" positive associations with the ICODT (r = 0.65; 41.8% shared-variance) and sprint tests (r ≥ 0.52; 27.3 to 34.8% shared-variance). In addition, results showed "moderate" negative associations between ICODT-BALL and strength, and power measures, as well as a "small" negative relationship with balance tests. In conclusion, the ICODT-BALL is a valid and reliable test to evaluate the ability to quickly change directions while ball dribbling in young soccer players. Therefore, practitioners can use the ICODT-BALL as a tool for talent identification.

Effects of Sand-Based Plyometric-Jump Training in Combination with Endurance Running on Outdoor or Treadmill Surface on Physical Fitness in Young Adult Males.

This study aimed at examining the effects of nine weeks of sand-based plyometric-jump training (PJT) combined with endurance running on either outdoor or treadmill surface on measures of physical fitness. Male participants (age, 20.1 ± 1.7 years) were randomly assigned to a sand-based PJT combined with endurance running on outdoor surface (OT, n = 25) or treadmill surface (TT, n = 25). The endurance running intervention comprised a mixed training method, i.e., long slow distance, tempo, and interval running drills. A control group was additionally included in this study (CG, n = 25). Participants in CG followed their regular physical activity as OT and TT but did not receive any specific intervention. Individuals were assessed for their 50-m linear sprint time, standing long jump (SLJ) distance, cardiorespiratory fitness (i.e., Cooper test), forced vital capacity (FVC), calf girth, and resting heart rate (RHR). A three (groups: OT, TT, CG) by two (time: pre, post) ANOVA for repeated measures was used to analyze the exercise-specific effects. In case of significant group-by-time interactions, Bonferroni adjusted paired (within-group) and independent (between-group comparisons at post) t-tests were used for post-hoc analyses. Significant group-by-time interactions were found for all dependent variables (p < 0.001 - 0.002, ɳp2 = 0.16 - 0.78). Group-specific post-hoc tests showed improvements for all variables after OT (p < 0.001, Hedges'g effect size [g] = 0.05 - 1.94) and TT (p < 0.001, g = 0.04 - 2.73), but not in the CG (p = 0.058 - 1.000, g = 0.00 - 0.34). Compared to CG, OT showed larger SLJ (p = 0.001), cardiorespiratory fitness (p = 0.004), FVC (p = 0.008), and RHR (p < 0.001) improvements. TT showed larger improvements in SLJ (p = 0.036), cardiorespiratory fitness (p < 0.001), and RHR (p < 0.001) compared with CG. Compared to OT, TT showed larger improvements for SLJ (p = 0.018). In conclusion, sand-based PJT combined with either OT or TT similarly improved most measures of physical fitness, with greater SLJ improvement after TT. Coaches may use both concurrent exercise regimes based on preferences and logistical constrains (e.g., weather; access to treadmill equipment).

The Interaction between Mobility Status and Exercise Specificity in Older Adults.

Many adults older than 60 yr experience mobility limitations. Although physical exercise improves older adults' mobility, differences in baseline mobility produce large variations in individual responses to interventions, and these responses could further vary by the type and dose of exercise. Here, we propose an exercise prescription model for older adults based on their current mobility status.

Effects of Exercise Dose and Detraining Duration on Mobility at Late Midlife: A Randomized Clinical Trial.

BACKGROUND: Office workers near retirement tend to be sedentary and can be prone to mobility limitations and diseases. We examined the dose effects of exergaming volume and duration of detraining on motor and cognitive function in office workers at late midlife to reduce sedentariness and mobility limitations. METHODS: In an assessor-blinded randomized trial, 160 workers aged 55-65 years performed physically active video games in a nonimmersive form of virtual reality (exergaming) in small, supervised groups for 1 h, 1×, 2×, or 3×/week for 8 weeks followed by detraining for 8 and 16 weeks. Exergaming comprises high-intensity, full-body sensorimotor coordination, balance, endurance, and strengthening exercises. The primary outcome was the 6-minute walk test (6MWT), and secondary outcomes were body mass, self-reported physical activity, sleep quality, Berg Balance Scale, Short Physical Performance Battery, fast gait speed, dynamic balance, heart rate recovery after step test, and 6 cognitive tests. RESULTS: The 3 groups were not different in any of the outcomes at baseline (all p > 0.05). The outcomes were stable and had acceptable reliability (intraclass correlation coefficients ≥0.334) over an 8-week control period. Training produced an inverted U-shaped dose response of no (1×), most (2×), and medium (3×/week) effects of exergaming volume in most motor and selected cognitive outcomes. The distance walked in the 6MWT (primary outcome) increased most (94 m, 19%, p < 0.05), medium (57 m, 12%, p < 0.05), and least (4 m, 1%) after exergaming 2×, 3×, or 0× (control) (all different p < 0.05). The highest responders tended to retain the exercise effects over 8 weeks of detraining, independent of training volume. This maintenance effect was less consistent after 16 weeks of detraining. CONCLUSION: Less was more during training and lasted longer after detraining. A medium dose volume of exergaming produced the largest clinically meaningful improvements in mobility and selected cognitive tests in 60-year-old office workers with mild mobility limitations and intact cognition.

The performance of balance exercises during daily tooth brushing is not sufficient to improve balance and muscle strength in healthy older adults.

BACKGROUND: High prevalence rates have been reported for physical inactivity, mobility limitations, and falls in older adults. Home-based exercise might be an adequate means to increase physical activity by improving health- (i.e., muscle strength) and skill-related components of physical fitness (i.e., balance), particularly in times of restricted physical activity due to pandemics. OBJECTIVE: The objective of this study was to examine the effects of home-based balance exercises conducted during daily tooth brushing on measures of balance and muscle strength in healthy older adults. METHODS: Fifty-one older adults were randomly assigned to a balance exercise group (n = 27; age: 65.1 ± 1.1 years) or a passive control group (n = 24; age: 66.2 ± 3.3 years). The intervention group conducted balance exercises over a period of eight weeks twice daily for three minutes each during their daily tooth brushing routine. Pre- and post-intervention, tests were included for the assessment of static steady-state balance (i.e., Romberg test), dynamic steady-state balance (i.e., 10-m single and dual-task walk test using a cognitive and motor interference task), proactive balance (i.e., Timed-Up-and-Go Test [TUG], Functional-Reach-Test [FRT]), and muscle strength (i.e., Chair-Rise-Test [CRT]). RESULTS: Irrespective of group, the statistical analysis revealed significant main effects for time (pre vs. post) for dual-task gait speed (p < .001, 1.12 ≤ d ≤ 2.65), TUG (p < .001, d = 1.17), FRT (p = .002, d = 0.92), and CRT (p = .002, d = 0.94) but not for single-task gait speed and for the Romberg-Test. No significant group × time interactions were found for any of the investigated variables. CONCLUSIONS: The applied lifestyle balance training program conducted twice daily during tooth brushing routines appears not to be sufficient in terms of exercise dosage and difficulty level to enhance balance and muscle strength in healthy adults aged 60-72 years. Consequently, structured balance training programs using higher exercise dosages and/or more difficult balance tasks are recommended for older adults to improve balance and muscle strength.

Non-local acute stretching effects on strength performance in healthy young adults.

BACKGROUND: Static stretching (SS) can impair performance and increase range of motion of a non-exercised or non-stretched muscle, respectively. An underdeveloped research area is the effect of unilateral stretching on non-local force output. OBJECTIVE: The objective of this review was to describe the effects of unilateral SS on contralateral, non-stretched, muscle force and identify gaps in the literature. METHODS: A systematic literature search following preferred reporting items for systematic review and meta-analyses Protocols guidelines was performed according to prescribed inclusion and exclusion criteria. Weighted means and ranges highlighted the non-local force output response to unilateral stretching. The physiotherapy evidence database scale was used to assess study risk of bias and methodological quality. RESULTS: Unilateral stretching protocols from six studies involved 6.3 ± 2 repetitions of 36.3 ± 7.4 s with 19.3 ± 5.7 s recovery between stretches. The mean stretch-induced force deficits exhibited small magnitude effect sizes for both the stretched (-6.7 ± 7.1%, d = -0.35: 0.01 to -1.8) and contralateral, non-stretched, muscles (-4.0 ± 4.9%, d = , 0.22: 0.08 to 1.1). Control measures exhibited trivial deficits. CONCLUSION: The limited literature examining non-local effects of prolonged SS revealed that both the stretched and contralateral, non-stretched, limbs of young adults demonstrate small magnitude force deficits. However, the frequency of studies with these effects were similar with three measures demonstrating deficits, and four measures showing trivial changes. These results highlight the possible global (non-local) effects of prolonged SS. Further research should investigate effects of lower intensity stretching, upper versus lower body stretching, different age groups, incorporate full warm-ups, and identify predominant mechanisms among others.