The finger flexors occlusion threshold in sport-climbers: an exploratory study on its indirect approximation

Blood flow partially determines specific climbing endurance (SCE) as it mediates oxygen bio-availability in the finger flexors. Blood flow is related to occlusion threshold (OT), which is defined as the contraction intensity at which intramuscular pressure exceeds perfusion blood pressure resulting in the cessation of local blood flow. The OT is represented as an inflection point on a force-time graph when isometric force is registered and applied through maximal and continuous tests. Endurance time (ET) to exhaustion is influenced by the relative isometric applied force and is different for each climber. The aim of this study was to explore whether an approximation of the finger flexors OT in sport climbers through records of ET to exhaustion at different isometric relative intensities was possible. We measured maximum finger hang ETs at 6 intensities ranging from 85% to 35% maximal force in 34 sport climbers of advanced and elite level. The values obtained were analysed by two different methods in an attempt to determine a change in the shape of the curve in the intensity-ET relationship graphs that approximated the OT for each climber. The results suggest that the finger flexors OT could be different among climbers, regardless of their strength and ability level. The presented methods do not accurately reflect the OT, but could indicate the intensity at which blood flow is restored in the active muscles. This is the first study to indirectly approximate the finger flexors OT in sport-climbers, a parameter that could be essential to assess SCE

Longitudinal effects of swimming on bone in adolescents: A pQCT and DXA study

The aims of the present study were, firstly, to evaluate areal bone mineral density (aBMD), bone strength and structure during a swimming season and compare them to those of normo-active controls (CG), and secondly to ascertain whether practising an additional weight-bearing sport other than swimming might improve bone. Twenty-three swimmers who only swam (SWI-PURE; 14 males, 9 females), 11 swimmers who combined swimming with an additional weight-bearing sport (SWI-SPORT; 8 males, 3 females) and 28 controls (CG; 16 males, 12 females) participated in the present study. aBMD was assessed with dual energy X-ray (DXA). Bone mass, area, structure and strength of the non-dominant tibia and radius were measured with peripheral quantitative computed tomography (pQCT). Measurements were performed at the beginning of the swimming season and 8 months later. The only difference among groups for DXA and pQCT variables was found for arm aBMD, which was higher in the SWI-SPORT than in the CG group at both pre- and post-evaluation. Group by time interactions (GxT) were found for trochanter aBMD when comparing SWI-SPORT to CG and SWI-SPORT to SWI-PURE, favouring in both cases SWI-SPORT. No GxT were found for the radius. For the tibia, GxT were found between SWI-SPORT and CG and between SWI-PURE and CG, in both cases favouring the swimmers. A season of swimming does not confer any additional benefits to aBMD, but may confer minor benefits to structure and mass. Complementing swimming with a weight-bearing activity is beneficial to bone

A new performance threshold in sport climbing: A change in how climbing trainers work?

Objectives: Previous research has shown that the finger flexor's occlusion threshold (OT) could be different among sport climbers when expressed as a percentage of their maximum finger force (OT%), and that there is no association between the OT% and the climberś ability level. The aim of the present study was to evaluate the possible association between the relative finger force applied at the OT% (rff-OT%) and climbing ability level. Equipment and methods: WWe approximated the finger flexor's OT of 34 sport climbers by finger hang endurance test analyses at different intensities between 35% and 85% of their individual maximum finger force on a previously individually adapted edge depth, and we valued their rff-OT% as the relative force they could perform at that intensity. Results: We found a high correlation between the rff-OT% and climbing ability in elite climbers. These findings suggest that having an OT at the highest possible percentage is critical, in addition to having a high relative finger force, as this would enable climbers to express relative force at a wider range of intensities with favorable metabolic conditions

Comparison Of Body Composition Methods For The Assessment Of Body Fat In Adolescent Soccer Players

Anthropometry, dual energy x-ray absorptiometry (DXA) and air displacement plethysmography (ADP) are widely used for assessing body fat percentage (%BF). The accuracy among body composition methods in different kind of populations such as children, adults, obese persons, and athletes has been studied but there are some discrepancies between them. PURPOSE: To compare %BF assessed by DXA, ADP and anthropometry in adolescent soccer players. METHODS: %BF was assessed in ninety-two soccer players (64 males, 13.3 ± 0.5 y; 28 females, 13.3 ± 0.6 y) by anthropometry, DXA and ADP. Anthropometry measurements were registered following the recommendations of the ISAK. Anthropometry %BF was calculated using the equation proposed by Slaughter et al for adolescents. ADP %BF was calculated with 3 different formulas: (i) the general Siri equation (ADPSiri); (ii) the age- and sex-specific equation by Lohman (ADPLohman) and (iii) the age- and sex-specific equation by Silva (ADPSilva). Agreement and differences between methods were assessed by two-paired samples t tests and calculating the 95% limits of agreement. RESULTS: In the whole sample, ADPSiri ADPLohman ADPSilva and anthropometry underestimated %BF by 2.0, 6.9, 6.2, and 6.0% respectively compared to DXA (all p<0.05). The 95% limits of agreement ranged from ±5.91% to ±10.78%. Similar results dividing by sex were found. CONCLUSION: Although the 3 used methodologies have been several times described as valid for the assessment of %BF, based in our data it seems that ADP, anthropometry and DXA are not interchangeable for the assessment of %BF in adolescent soccer players

Impact of the covid-19 pandemic on teacher quality of life: A longitudinal study from before and during the health crisis

Background: Prior to the COVID-19 pandemic, teachers were already reporting a low quality of life (QoL) perception, with a significant impact on mental and physical health due to various stress factors associated with work overload. The objective of this study was to evaluate the QoL impact on Chilean teachers before and during the COVID-19 pandemic. The analysis was performed following a longitudinal design on a sample of 63 Chilean teachers in pre-pandemic and COVID-19 pandemic timeframes. QoL perception, along with teachers’ sociodemographic data, was evaluated via the Short-Form 36 Health Survey (SF-36) questionnaire. Sociodemographic variables presented no significant variations in pre-pandemic and pandemic comparisons. QoL, however, showed a significant decrease during the pandemic compared to the pre-pandemic measurement (p < 0.01). In each gender, there were significant differences between pre-pandemic and pandemic timeframes, with a greater impact among women in the mental and physical component summary variables and seven of the eight QoL scales (p < 0.01). Between age categories, people under 45 presented significant differences (p < 0.05) between pre-pandemic and pandemic timeframes in all summary dimensions and measurements. In conclusion, Chilean teachers’ QoL perception has been affected by the COVID-19 pandemic. These findings could be related to work overload due to teleworking or feelings of uncertainty, loneliness, and fear that the pandemic and its associated confinements will worsen

Longitudinal Effects Of Swimming On Bone Mass, Structure And Strength

PURPOSE: To investigate the changes over a swimming season in bone mineral density (BMD), bone mineral content (BMC), bone strength and bone structure in adolescent swimmers and compared them to normo-active controls (CG). METHODS: BMD and BMC were measured longitudinally (8 months) by Dual Energy X-ray Absorptiometry at the whole body, lumbar spine and non-dominant hip. Bone strength was measured at the midshaft radius and tibia with peripheral quantitative computed tomography (pQCT). Swimmers were divided into two groups; swimmers that swam and performed an extra-weight bearing sport (SWI-SPORT; n=11) and swimmers that only swam (SWI; n=23). Both groups were compared between them and to CG (n=28). ANCOVA for repeated measures x 2 (time) were performed between pre- and post-intervention to determine the effects of swimming on BMC and BMD values adjusting by change in height and subtotal lean, initial age and final Tanner stage and calcium intake for DXA values. For pQCT the same analyses were performed adjusting by change in object length, initial age and final Tanner stage. RESULTS: Eight months of swimming training had no effect on BMD or BMC, as no differences were found between SWI-PURE and CG acquisition. Nevertheless, practicing an extra-weight bearing sport in addition to swimming seemed to positively stimulate bone mass acquisition as SWI-SPORT was the only group that improved all measured skeletal sites and also a group by time interaction was found for the trochanter and total hip BMD when comparing SWI-SPORT to CG (p<0.05). Regarding pQCT measures, no group by time interactions were found for the radius. For the tibia, SWI-SPORT presented higher improvements in cortical thickness, resistance to fracture load (X-axis), and polar strain index than CG (all group by time interactions p<0.05). SWI-PURE also presented higher improvements in polar strain index when compared to CG (group by time interaction p<0.05). CONCLUSION: Swimming seems to be a neutral sport to practice regarding BMD and BMC acquisition. Nevertheless, it might entail some minor improvements in bone strength. Practicing a weight bearing sport in addition to swimming improves both bone mass acquisition and bone strength

The muscle-bone unit in adolescent swimmers

Most researchers adjust bone by lean mass when comparing swimmers with controls. This adjustment is done under the assumption that lean affects bone similarly in both groups. Nonetheless, we found that the muscle-bone association is uncoupled in swimmers, and consequently, researchers should avoid this adjustment when evaluating swimmers’ bone. Introduction: To examine the functional and structural muscle-bone unit in adolescent swimmers. Methods: Sixty-five swimmers (34 girls/31 boys) and 119 controls (51 girls/68 boys) participated in the study. Muscle cross-sectional area (MCSA), bone mineral content (BMC), and polar strength-strain index (SSIPOL) were measured in the non-dominant radius by peripheral quantitative computed tomography (pQCT). Subtotal BMC and lean mass were evaluated with dual-energy X-ray absorptiometry (DXA). Handgrip and isometric knee extension (IKE) tests were performed to determine muscle force. The effect of MCSA, lean and force on SSIPOL, and BMC were tested, and the functional and structural muscle-bone ratios of swimmers and controls were compared. Results: Both muscle size (MCSA and lean) and muscle force (handgrip and IKE) influenced BMC and SSIPOL in swimmers and controls similarly. Swimmers presented normal MCSA and lean values for their height, but when compared with controls, swimmers presented a higher amount of lean and MCSA for the same BMC or SSIPOL (structural muscle-bone unit). For the functional muscle-bone unit, different results were found for the lower and upper limbs, as no differences were found for the upper limbs, while for the lower limbs, swimmers presented higher muscle force for the same amount of BMC. Conclusions: The contradictory results regarding BMC in swimmers found in previous studies could partly be explained with the findings of the present study that reinforce the idea that swimming is not an effective sport to practice regarding bone mass and that the muscle-bone unit is different in swimmers than in controls

Do 6 Months Of Whole Body Vibration Training Improve Bone Mass Acquisition Of Adolescent Swimmers?

Whole body vibration (WBV) training has been suggested to be an effective type of training for improving bone mass. PURPOSE: To determine the effects of WBV training on bone mass acquisition in adolescent swimmers. METHODS: Sixty-four swimmers were followed over 8 months. Participants were divided in to two groups: The first group consisted of forty-one swimmers (14.2±1.8 y) who completed a WBV protocol 15 minutes of training 3 days per week during 6 months (WBV training increased each month starting with a peak acceleration of 3.6 g and ending at 11.6 during the last month) while continuing with their habitual water training (VIB). The second group consisted of twenty-three swimmers (15.0±2.2 y) who continued with their regular swimming training (SWI) (both groups performed an average of 10 hours per week of water training). Bone mineral density (BMD) and content (BMC) were measured longitudinally (8 months) by Dual Energy X-ray Absorptiometry at the whole body, lumbar spine and non-dominant hip. Analysis of covariance (ANCOVA) for repeated measures x2 (time) were performed to check differences within groups between pre and post intervention and to determine the effects of the intervention on BMD and BMC values adjusting by change in height and subtotal lean, initial age and final Tanner stage and calcium intake. RESULTS: Six months of WBV training had little effect on bone mass, as no differences were found between VIB and SWI for absolute change or percentage change for BMD values. For BMC, VIB presented higher absolute and percentage changes in both trochanter (7% increase in VIB vs. 3% in SWI) and total hip (6% increase in VIB vs. 3% in SWI) than SWI, although there was no group by time interaction. CONCLUSION: WBV training might entail minor benefits to BMC acquisition in adolescent swimmers. A minimum compliance of sixty percent was needed to improve BMC, which in the present study consisted of attending at least 2 of the 3 weekly days of training. Future studies using WBV should try to perform more sessions per week at higher intensities to determine if this type of training could be highly beneficial to bone or if other high-impact trainings might be more suitable to improve bone mass in this population

Does acute caffeine supplementation improve physical performance in female team-sport athletes? Evidence from a systematic review and meta-analysis

Introduction: Recent original research and meta-analyses suggest that acute caffeine supplementation improves exercise performance in team-sport athletes (TSA). Nonetheless, most of the studies testing the effects of caffeine on TSA included samples of male athletes, and there is no meta-analysis of the performance-enhancing effects of caffeine on female TSA. The aim of the present study was to synthesize the existing literature regarding the effect of caffeine supplementation on physical performance in adult female TSA. Methods: A search was performed in Pubmed/Medline, SPORTDiscus and Scopus. The search was performed from the inception of indexing until 1 Sep-tember 2021. Crossover randomized controlled trials (RCT) assessing the effects of oral caffeine intake on several aspects of performance in female TSA were selected. The methodological quality and risk of bias were assessed for individual studies using the Physiotherapy Evidence Database scale (PEDro) and the RoB 2 tool. A random-effects meta-analysis of standardized mean differences (SMD) was performed for several performance variables. Results: The search retrieved 18 articles that fulfilled the inclusion/exclusion criteria. Overall, most of the studies were of excellent quality with a low risk of bias. The meta-analysis results showed that caffeine increased performance in specific team-sport skills (SMD: 0.384, 95% confidence interval (CI): 0.077–0.691), countermovement jump (SMD: 0.208, CI: 0.079–0.337), total body impacts (SMD: 0.488; 95% CI: 0.050, 0.927) and hand-grip strength (SMD: 0.395, CI: 0.126–0.665). No effects were found on the ratings of perceived exertion, squat jumps, agility, repeated sprint ability or agility tests performed after fatigue. Conclusions: The results of the meta-analysis revealed that acute caffeine intake was effective in increasing some aspects of team-sports performance in women athletes. Hence, caffeine could be considered as a supplementation strategy for female athletes competing in team sports. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Effects Of Playing Surfaces On Volumetric Bone Mineral Density In Adolescent Male Soccer Players

It has been well recognized that impact loading in sporting activity is highly associated with bone accretion. Recently, Carmona et al. showed that bone mass accretion was similar bone in prepubescent soccer players independently of the playing surface (artificial turf vs. non-grass ground surface). However, the osteogenic effects on volumetric bone mineral density (vBMD) generated by four different playing surfaces of the same sport are unknown. PURPOSE: to investigate the effects over a soccer season in vBMD of male soccer players by playing surface. METHODS: A total of 71 male soccer players (12.7±0.6 y) volunteered to participate in the study. 26 participants were training and playing on 2nd generation artificial turf, 16 on a 3rd generation artificial turf, 10 on a non-grass ground surface and 19 on natural grass (NG). vBMD, at 4 and 38% of the non-dominant tibia, was measured before and after season by peripheral quantitative computed tomography (Stratec XCT-2000 L pQCT scanner). Analysis of variance for repeated measures×2 (time) were performed to determine the effects of playing surface on vBMD controlling for pubertal status. Effect size were calculated according to the methods proposed by Cohen (small (f=0.1), medium (f=0.2), or large (f=0.4)). RESULTS: A group by time interaction was found for vBMD at 38% of the distal tibia (p=0.029 and f=0.38). When pairwise comparisons were carried out, NG showed group by time interactions compared to 2nd generation artificial turf (782 to 804 mg/cm3 vs. 790 to 798 mg/cm3; p=0.007 and f=0.50), and to 3rd generation artificial turf (782 to 804 mg/cm3 vs. 784 to 788 mg/cm3; p=0.027 and f=0.35). CONCLUSION: Soccer players training and playing in NG pitch showed better values in vBMD acquisition than those on 2nd and 3rd generation artificial turf. Despite previous studies presented no differences on bone mass accretion independently of the playing surface. Our results suggest that NG is the most recommended playing surface to improve vBMD in the non-dominant tibia