Aging effects of haptic input on postural control under a dual-task paradigm.

Postural control relies on three principal sensory systems: vision, vestibular and proprioceptive; that are affected by aging. When performing a cognitive task concomitantly with a motor task, those sensory impairments lead to even greater deleterious effects on balance. We aimed to study the effects of a sensory aid (a light touch) on a dual task paradigm and sought to understand the different responses on balance due to aging. Fifty healthy and highly physical active women were divided in two groups: young (N = 25, 24.2 ± 4.0 years) and older adults (N = 25, 67.3 ± 4.2 years). In a random and balanced order, all participants performed five tasks: Stroop test while seated (Seated); Stroop test while standing quiet (ST); Standing quiet (BL); Standing quiet with a haptic input (LT); and Stroop test with a haptic input while standing quiet (SL). In the Stroop test, older women committed more errors (50 vs 11 errors, p < 0.001) and had higher reaction time (1.001 ± 0.191 vs 0.699 ± 0.081 s, p < 0.001). The haptic input (LT) reduced all body sway parameters, in both groups, regardless the condition. This means that postural control under a dual task paradigm (ST) deleterious effect can be mitigated by a haptic input.

Risk or benefit? Side effects of caffeine supplementation in sport: a systematic review.

PURPOSE: The aim of this study was to systematically review evidence on the prevalence and magnitude of side effects associated with caffeine supplementation in athletes. METHODS: Systematic searches through the PubMed, VHL, Scopus, and Web of Science databases were conducted according to the PRISMA guidelines. Peer-reviewed articles written in English that reported the prevalence/percentage or magnitude/effect size of side effects after caffeine supplementation in athletes in a sports context were included. Studies were grouped by the dose of caffeine administered as follows: low = ≤ 3.0 mg/kg; moderate = from 3.1 to 6.0 mg/kg; high = ≥ 6.1 mg/kg. The magnitude of the side effects was calculated with effect sizes. RESULTS: The search retrieved 25 studies that met the inclusion/exclusion criteria with a pooled sample of 421 participants. The supplementation with caffeine produced a higher prevalence or magnitude of all side effects under investigation when compared to placebo/control situations. The prevalence (magnitude) was between 6 and 34% (ES between 0.13 and 1.11) for low doses of caffeine, between 0 and 34% (ES between -0.13 and 1.20) for moderate doses of caffeine, and between 8 and 83% (ES between 0.04 and 1.52) with high doses of caffeine. The presence of tachycardia/heart palpitations and the negative effects on sleep onset had the highest prevalence and magnitude, in athletes using supplementation with caffeine. CONCLUSION: In summary, caffeine supplementation in the doses habitually used to enhance physical performance produces several side effects, both after exercise and at least 24 h after the ingestion. However, the prevalence and magnitude of side effects with high doses of caffeine were habitually higher than with low doses of caffeine. From a practical perspective, using ~3.0 mg/kg of caffeine may be the dose of choice to obtain the ergogenic benefits of caffeine with the lowest prevalence and magnitude of side effects.

Strength Training to Prevent Falls in Older Adults: A Systematic Review with Meta-Analysis of Randomized Controlled Trials.

We performed a systematic review with meta-analysis of randomized controlled trials (RCTs) to assess the effects of strength training (ST), as compared to alternative multimodal or unimodal exercise programs, on the number of falls in older adults (≥60 years). Ten databases were consulted (CINAHL, Cochrane Library, EBSCO, EMBASE, PEDro, PubMed, Scielo, Scopus, SPORTDiscus and Web of Science), without limitations on language or publication date. Eligibility criteria were as follows: RCTs with humans ≥60 years of age of any gender with one group performing supervised ST and a group performing another type of exercise training, reporting data pertaining falls. Certainty of evidence was assessed with Grading of Recommendations, Assessment, Development and Evaluation (GRADE). Meta-analysis used a random effects model to calculate the risk ratio (RR) for number of falls. Five RCTs with six trials were included (n = 543, 76% women). There was no difference between ST and alternative exercise interventions for falls (RR = 1.00, 95% CI 0.77-1.30, p = 0.99). The certainty of evidence was very low. No dose-response relationship could be established. In sum, ST showed comparable RR based on number of falls in older adults when compared to other multimodal or unimodal exercise modalities, but evidence is scarce and heterogeneous, and additional research is required for more robust conclusions. Registration: PROSPERO CRD42020222908.

Eccentric Strength Assessment of Hamstring Muscles with New Technologies: a Systematic Review of Current Methods and Clinical Implications.

BACKGROUND: Given the severe economic and performance implications of hamstring injuries, there are different attempts to identify their risk factors for subsequently developing injury prevention strategies to reduce the risk of these injuries. One of the strategies reported in the scientific literature is the application of interventions with eccentric exercises. To verify the effectiveness of these interventions, different eccentric strength measurements have been used with low-cost devices as alternatives to the widespread used isokinetic dynamometers and the technically limited handheld dynamometers. Therefore, the purpose of the present systematic review was to summarize the findings of the scientific literature related to the evaluation of eccentric strength of hamstring muscles with these new technologies. METHODS: Systematic searches through the PubMed, Scopus, and Web of Science databases, from inception up to April 2020, were conducted for peer reviewed articles written in English, reporting eccentric strength of hamstrings assessed by devices, different to isokinetic and handheld dynamometers, in athletes. RESULTS: Seventeen studies were finally included in the review with 4 different devices used and 18 parameters identified. The pooled sample consisted of 2893 participants (97% male and 3% female: 22 ± 4 years). The parameters most used were peak force (highest and average), peak torque (average and highest), and between-limb imbalance (left-to-right limb ratio). There is inconsistency regarding the association between eccentric hamstrings strength and both injury risk and athletic performance. There is no standardized definition or standardization of the calculation of the used parameters. CONCLUSIONS: The current evidence is insufficient to recommend a practical guide for sports professionals to use these new technologies in their daily routine, due to the need for standardized definitions and calculations. Furthermore, more studies with female athletes are warranted. Despite these limitations, the eccentric strength of hamstring muscles assessed by different devices may be recommended for monitoring the neuromuscular status of athletes.

Perception of impact is affected by stimulus intensity.

Perception of external loads may be a central topic to understand adjustments to the mechanical demands during movement. Nevertheless, the association between the perceived and the real load received is still controversial. This study aimed to correlate vertical ground reaction force (vGRF) to the perception of impact in different regimens of stimulus application. Ten physically active men performed drop jumps from four different heights (0.20, 0.40, 0.60 and 0.80 m). A force plate measured the vGRF, while perception of impact was evaluated through Borg's Ratings of Perceived Exertion. Higher values of maximum vGRF (Fy_max) and impulse of the first 50 ms (I_50), and reduced time to reach Fy_max indicate increased external forces as drop jump height raised. Perception of impact increased gradually with increasing jump height for I_50. Fy_max and I_50 showed moderate to strong correlations to perceived load for 70% and 90% of participants, respectively. Higher and different intensity of stimulus facilitated the perception of impact, presenting moderate to strong correlations to kinetic parameters related to external load during landing from drop jump. Perception of higher impacts could be used as a surrogate to monitor 'real' impacts and possibly also for managing impact-related injury risk.

Overall indexes of coordination in front crawl swimming.

The aim of this study was to propose a group of parameters able to quantify not only arm coordination but also inter limb coordination. These include the well know index of coordination with the relative duration of the stroke phases and two new parameters: the Index of synchronization (Ids) between arms and legs actions; and the Index of inter limb coordination (IdIC) calculated as the relative foot position during successive arm stroke phases. These parameters were compared between experts and amateur swimmers in a maximal front crawl sprint. The influence of arm stroke in leg kick parameters was also assessed, comparing the full stroke condition with a condition without arms actions. Sixty-five per cent of expert swimmers used synchronized limb actions while 95% of amateur swimmers used non-synchronized limb motions. These synchronized expert swimmers also converged towards a specific coordination pattern between foot position and arm stroke phases. In the condition without arms, both groups changed kick rate and amplitude. The present study reveals the interdependency of arms and legs actions and the importance of coordination and synchronization between limbs. Therefore, the proposed group of overall indexes of coordination provides a more complete marker for the analysis of swimming technique.

A High-Intensity Exercise Intervention Improves Older Women Lumbar Spine and Distal Tibia Bone Microstructure and Function: A 20-Week Randomized Controlled Trial.

Introduction: The effects of ageing on bone can be mitigated with different types of physical training, such as power training. However, stimuli that combine increasing external and internal loads concomitantly may improve bone quality. The goal of this study was to assess the efficacy of a combined power and plyometric training on lumbar spine and distal tibia microstructure and function. Methods: 38 sedentary elderly women between 60 and 70 years were randomly allocated in experimental (N = 21) and control group (N = 17). The effects of the 20-week protocol on lumbar spine microstructure and tibia microstructure and function were assessed by trabecular bone score (TBS), high resolution peripheral quantitative computed tomography (HR-pQCT) and microfinite element analysis. Results: when compared to the effects found in the control group, the experimental group showed significant improvements in lumbar spine TBS (Hedges' g = 0.77); and in distal tibia trabecular thickness (g = 0.82) and trabecular bone mineral density (g=0.63). Conclusion: our findings underscore the effectiveness of the proposed intervention, suggesting it as a new strategy to slow down and even reverse the structural and functional losses in the skeletal system due to ageing.

Back Squat vs. Hip Thrust Resistance-training Programs in Well-trained Women.

The study compared the effects of back squat (BS) and hip thrust (HT) exercises on muscle strength and hypertrophy in well-trained women. Twenty-two participants were divided in two groups: BS group (n=12, 26.4±1.32 years, 171.8±3.79 cm, and 69.5±4.9 kg) performed the BS exercise and HT group (n=10, 27.5±1.42 years, 170.8±4.4 cm, 67.5±4.7 kg) performed the HT exercise. Training was performed for 12 weeks. Before and after the training period, participants were assessed for quadriceps femoris and gluteus maximus muscle thickness (MT) and 1 repetition maximum (1RM) test on the BS and HT. Both groups significantly increased hip extensors MT and HT 1RM; however, the improvements in BS group were higher than in HT group on quadriceps femoris (12.2% for BS and 2% for HT, P<0.001) and gluteus maximus MT (9.4% for BS and 3.7% for HT, P=0.001) and BS 1 RM (35.9% for BS and 4.3% for HT, P<0.001). BS was more efficient than HT, since it resulted in greater muscle hypertrophy of the quadriceps femoris and gluteus maximus, increases in BS 1RM and similar increases in HT.

Muscle stretching changes neuromuscular function involved in ankle stability.

It has been postulated that the mechanical and neurophysiological effects induced by stretching decrease maximal muscle strength and power. Additionally, the reduction in neural input and muscle stiffness can affect the joint stabilization process. However, there is no evidence available to support this hypothesis. Thus, the aim of this study is to analyze the influence of static stretching on dynamic joint stability. Twenty physically active female university students (22.8 ± 5.3 years; 58 ± 8.8 kg; 1.62 ± 0.07 m) performed a series of static-passive stretching exercises for the peroneus longus and brevis muscles (four repetitions of 30 s). Before and after the stretches, electromyography was performed on both muscles during simulated ankle sprain. Mathematical algorithms calculate the latency and the electromyography activity (RMS). After stretching, the latency increased from 66ms to 73 ms (p = 0.003) for the peroneus brevis muscle and from 70 ms to 79 ms (p = 0.001) for the peroneus longus muscle. The RMS, calculated 100 ms after the simulation, decreased in the peroneus brevis muscle, from 25.05 to 18.16 (p = 0.001), and in the peroneus longus muscle, from 22.84 to 15.61 (p = 0.001). Muscle stretching changed the motor responses of both muscles. The increase in latency and the decrease in RMS indicate that static stretching influences the neuromuscular function involved in the joint stabilization process.

Sleep quality monitoring in individual sports athletes: parameters and definitions by systematic review.

In the present review, we identify which instruments and parameters are used for sleep quality monitoring in individual sport athletes and which definitions were used for sleep quality parameters in this literature field. Systematic searches for articles reporting the qualitative markers related to sleep in team sport athletes were conducted in PubMed, Scopus and Web of Science online databases. The systematic review followed the Preferred Reporting Items for Systematic Reviews. The initial search returned 3316 articles. After the removal of duplicate articles, eligibility assessment, 75 studies were included in this systematic review. Our main findings were that the most widely used measurement instruments were Actigraphy (25%), Rating Likert Scales (16%) and Sleep Diary (13%). On sleep quality parameters (Sleep duration = 14%; Wake after sleep onset = 14%; Sleep Quality = 12%; Sleep Effciency = 11% and Sleep Latency = 9%), the main point is that there are different definitions for the same parameters in many cases reported in the literature. We conclude that the most widely used instruments for monitoring sleep quality were Actigraphy, Likert scales and Sleep diary. Moreover, the definitions of sleep parameters are inconsistent in the literature, hindering the understanding of the sleep-sport performance relationship.