Jesús G. Pallarés

Validity of Hydration Non-Invasive Indices during the Weightcutting and Official Weigh-In for Olympic Combat Sports

Background In Olympic combat sports, weight cutting is a common practice aimed to take advantage of competing in weight divisions below the athletes normal weight. Fluid and food restriction in combination with dehydration (sauna and/or exercise induced profuse sweating) are common weight cut methods. However, the resultant hypohydration could adversely affect health and performance outcomes. Purpose The aim of this study is to determine which of the routinely used non-invasive measures of dehydration best track urine osmolality, the gold standard non-invasive test. Method Immediately prior to the official weigh-in of three National Championships, the hydration status of 345 athletes of Olympic combat sports (i.e., taekwondo, boxing and wrestling) was determined using five separate techniques: i) urine osmolality (UOSM), ii) urine specific gravity (USG), iii) urine color (UCOL), iv) bioelectrical impedance analysis (BIA), and v) thirst perception scale (TPS). All techniques were correlated with UOSM divided into three groups: euhydrated (G1; UOSM 250–700 mOsm·kg H2O−1), dehydrated (G2; UOSM 701–1080 mOsm·kg H2O−1), and severely dehydrated (G3; UOSM 1081–1500 mOsm·kg H2O−1). Results We found a positive high correlation between the UOSM and USG (r = 0.89: p = 0.000), although this relationship lost strength as dehydration increased (G1 r = 0.92; G2 r = 0.73; and G3 r = 0.65; p = 0.000). UCOL showed a moderate although significant correlation when considering the whole sample (r = 0.743: p = 0.000) and G1 (r = 0.702: p = 0.000) but low correlation for the two dehydrated groups (r = 0.498–0.398). TPS and BIA showed very low correlation sizes for all groups assessed. Conclusion In a wide range of pre-competitive hydration status (UOSM 250–1500 mOsm·kg H2O−1), USG is highly associated with UOSM while being a more affordable and easy to use technique. UCOL is a suitable tool when USG is not available. However, BIA or TPS are not sensitive enough to detect hypohydration at official weight-in before an Olympic combat championship.

Higher Insulin-sensitizing Response after Sprint Interval Compared to Continuous Exercise

This study investigated which exercise mode (continuous or sprint interval) is more effective for improving insulin sensitivity. Ten young, healthy men underwent a non-exercise trial (CON) and 3 exercise trials in a cross-over, randomized design that included 1 sprint interval exercise trial (SIE; 4 all-out 30-s sprints) and 2 continuous exercise trials at 46% VO2peak (CELOW) and 77% VO2peak (CEHIGH). Insulin sensitivity was assessed using intravenous glucose tolerance test (IVGTT) 30 min, 24 h and 48 h post-exercise. Energy expenditure was measured during exercise. Glycogen in vastus lateralis was measured once in a resting condition (CON) and immediately post-exercise in all trials. Plasma lipids were measured before each IVGTT. Only after CEHIGH did muscle glycogen concentration fall below CON (P<0.01). All exercise treatments improved insulin sensitivity compared with CON, and this effect persisted for 48-h. However, 30-min post-exercise, insulin sensitivity was higher in SIE than in CELOW and CEHIGH (11.5±4.6, 8.6±5.4, and 8.1±2.9 respectively; P<0.05). Insulin sensitivity did not correlate with energy expenditure, glycogen content, or plasma fatty acids concentration (P>0.05). After a single exercise bout, SIE acutely improves insulin sensitivity above continuous exercise. The higher post-exercise hyperinsulinemia and the inhibition of lipolysis could be behind the marked insulin sensitivity improvement after SIE.

Estimation of Relative Load From Bar Velocity in the Full Back Squat Exercise

The use of bar velocity to estimate relative load in the back squat exercise was examined. 80 strength-trained men performed a progressive loading test to determine their one-repetition maximum (1RM) and load-velocity relationship. Mean (MV), mean propulsive (MPV) and peak (PV) velocity measures of the concentric phase were analyzed. Both MV and MPV showed a very close relationship to %1RM (R 2 =0.96), whereas a weaker association (R 2 =0.79) and larger SEE (0.14 vs. 0.06 m·s −1 ) were found for PV. Prediction equations to estimate load from velocity were obtained. When dividing the sample into 3 groups of different relative strength (1RM/body mass), no differences were found between groups for the MPV attained against each %1RM. MV attained with the 1RM was 0.32±0.03 m·s −1 . The propulsive phase accounted for ~82% of concentric duration at 40% 1RM, and progressively increased until reaching 100% at 1RM. Provided that repetitions are performed at maximal intended velocity, a good estimation of load (%1RM) can be obtained from mean velocity as soon as the first repetition is completed. This finding provides an alternative to the often demanding, time-consuming and interfering 1RM or nRM tests and allows implementing a velocity-based resistance training approach.

Pseudoephedrine and circadian rhythm interaction on neuromuscular performance

This study analyzed the effects of pseudoephedrine (PSE) provided at different time of day on neuromuscular performance, side effects, and violation of the current doping cut‐off threshold [World Anti‐Doping Agency (WADA)]. Nine resistance‐trained males carried out bench press and full squat exercises against four incremental loads (25%, 50%, 75%, and 90% one repetition maximum [1RM]), in a randomized, double‐blind, cross‐over design. Participants ingested either 180 mg of PSE (supra‐therapeutic dose) or placebo in the morning (7:00 h; AMPLAC and AMPSE) and in the afternoon (17:00 h; PMPLAC and PMPSE). PSE enhanced muscle contraction velocity against 25% and 50% 1RM loads, only when it was ingested in the mornings, and only in the full squat exercise (4.4–8.7%; P < 0.05). PSE ingestion raised urine and plasma PSE concentrations (P < 0.05) regardless of time of day; however, cathine only increased in the urine samples. PSE ingestion resulted in positive tests occurring in 11% of samples, and it rose some adverse side effects such us tachycardia and heart palpitations. Ingestion of a single dose of 180 mg of PSE results in enhanced lower body muscle contraction velocity against low and moderate loads only in the mornings. These mild performance improvements are accompanied by undesirable side effects and an 11% risk of surpassing the doping threshold.

Muscle contraction velocity, strength and power output changes following different degrees of hypohydration in competitive olympic combat sports

BackgroundIt is habitual for combat sports athletes to lose weight rapidly to get into a lower weight class. Fluid restriction, dehydration by sweating (sauna or exercise) and the use of diuretics are among the most recurrent means of weight cutting. Although it is difficult to dissuade athletes from this practice due to the possible negative effect of severe dehydration on their health, athletes may be receptive to avoid weight cutting if there is evidence that it could affect their muscle performance. Therefore, the purpose of the present study was to investigate if hypohydration, to reach a weight category, affects neuromuscular performance and combat sports competition results.MethodsWe tested 163 (124 men and 39 woman) combat sports athletes during the 2013 senior Spanish National Championships. Body mass and urine osmolality (UOSM) were measured at the official weigh-in (PRE) and 13–18 h later, right before competing (POST). Athletes were divided according to their USOM at PRE in euhydrated (EUH; UOSM 250–700 mOsm · kgH2O−1), hypohydrated (HYP; UOSM 701–1080 mOsm · kgH2O−1) and severely hypohydrated (S-HYP; UOSM 1081–1500 mOsm · kgH2O−1). Athletes’ muscle strength, power output and contraction velocity were measured in upper (bench press and grip) and lower body (countermovement jump - CMJ) muscle actions at PRE and POST time-points.ResultsAt weigh-in 84 % of the participants were hypohydrated. Before competition (POST) UOSM in S-HYP and HYP decreased but did not reach euhydration levels. However, this partial rehydration increased bench press contraction velocity (2.8-7.3 %; p < 0.05) and CMJ power (2.8 %; p < 0.05) in S-HYP. Sixty-three percent of the participants competed with a body mass above their previous day’s weight category and 70 of them (69 % of that sample) obtained a medal.ConclusionsHypohydration is highly prevalent among combat sports athletes at weigh-in and not fully reversed in the 13–18 h from weigh-in to competition. Nonetheless, partial rehydration recovers upper and lower body neuromuscular performance in the severely hypohydrated participants. Our data suggest that the advantage of competing in a lower weight category could compensate the declines in neuromuscular performance at the onset of competition, since 69 % of medal winners underwent marked hypohydration.

Hormonal and neuromuscular responses during a singles match in male professional tennis players

We sought to measure the response of cortisol concentrations around a professional tennis match and its association with hydration status and neuromuscular performance. Nine professional male tennis players were tested in a rest day, and 2-week after, during the first match of a professional tournament played in a clay-court. Salivary concentrations of cortisol (SalCC) were measured in a resting day (9:00 am and 8:00 pm), at the match day (9:00 am and 8:00 pm) and immediately before and after the match. Hydration status was assessed before the match (urine specific gravity; USG) while fluid turnover was tracked during the match. Finally, counter movement jump (CMJ) and handgrip isometric strength (HS) were measured before and after the match. SalCC, either in the morning (P = 0.161) and afternoon (P = 0.683) was similar in rest and match days. However, SalCC increased after the match (P = 0.033). Participants started the match hypohydrated (USG = 1.026±0.002) and during the match lost 1.0±0.3% of body weight despite 1.035±0.124 L/h of fluid ingested. CMJ and HS did not change post-match (P = 0.210 and P = 0.881, respectively). Correlations between the elevations in SalCC and dehydration (% BW loss) during the match were significant (r = -0.632; P = 0.034). Professional male tennis players did not show an anticipatory increase in SalCC the day of the match and neither signs of neuromuscular fatigue after it. During the match, the mild dehydration (i.e., <1.5%) was associated with the increases in cortisol levels which suggests that dehydration may be an added stress to be considered.

Effects of aerobic interval training on arterial stiffness and microvascular function in patients with metabolic syndrome

The authors determined the effect of high‐intensity aerobic interval training on arterial stiffness and microvascular dysfunction in patients with metabolic syndrome with hypertension. Applanation tonometry was used to measure arterial stiffness and laser Doppler flowmetry to assess microvascular dysfunction before and after 6 months of stationary cycling (training group; n = 23) in comparison to a group that remained sedentary (control group; n = 23). While no variable improved in controls, hypertension fell from 79% (59%–91%) to 41% (24%–61%) in the training group, resulting in lower systolic and diastolic pressures than controls (−12 ± 3 and −6 ± 2 mm Hg, P < .008). Arterial stiffness declined (−17% augmentation index, P = .048) and reactive hyperemia increased (20%, P = .028) posttreatment in the training group vs controls. Blood constituents associated with arterial stiffness and a prothrombotic state (high‐sensitivity C‐reactive protein, fibrinogen, platelets, and erythrocytes) remained unchanged in the training and control groups. In summary, 6 months of an intense aerobic exercise program reduced both arterial stiffness and microvascular dysfunction in patients with metabolic syndrome despite unchanged blood‐borne cardiovascular risk factors. Training lowers blood flow resistance in central and peripheral vascular beds in a coordinated fashion, resulting in clinically relevant reductions in hypertension.

Acute Hypotension after High-Intensity Interval Exercise in Metabolic Syndrome Patients

The purpose of this study was to compare the magnitude of post-exercise hypotension (PEH) after a bout of cycling exercise using high-intensity interval training (HIIT) in comparison to a bout of traditional moderate-intensity continuous exercise (CE). After supine rest 14 obese (31±1 kg·m-2) middle-age (57±2 y) metabolic syndrome patients (50% hypertensive) underwent a bout of HIIT or a bout of CE in a random order and then returned to supine recovery for another 45 min. Exercise trials were isocaloric and compared to a no-exercise trial (CONT) of supine rest for a total of 160 min. Before and after exercise we assessed blood pressure (BP), heart rate (HR), cardiac output (Q), systemic vascular resistance (SVR), intestinal temperature (TINT), forearm skin blood flow (SKBF) and percent dehydration. HIIT produced a larger post-exercise reduction in systolic blood pressure than CE in the hypertensive group (-20±6 vs. -5±3 mmHg) and in the normotensive group (-8±3 vs. -3±2 mmHg) while HIIT reduced SVR below CE (P<0.05). Percent dehydration was larger after HIIT, and post-exercise TINT and SKBF increased only after HIIT (all P<0.05). Our findings suggest that HIIT is a superior exercise method to CE to acutely reduce blood pressure in MSyn subjects.

Technical Note on Using the Movement Velocity to Estimate the Relative Load in Resistance Exercises – Response

Dear Editor, Thank you for the opportunity to respond to the points ra ised by Nacler io & Larumbe-Zabala regarding our recent article [5] in Sports Medicine International Open. This study provided a detailed description of the load-velocity relationship in the full back squat exercise along with the novel and very important applications that can be derived from this relationship for the practice of resistance exercise.

Habituation Training Improves Locomotor Performance in a Forced Running Wheel System in Rats

Increasing evidence supports that physical activity promotes mental health; and regular exercise may confer positive effects in neurological disorders. There is growing number of reports that requires the analysis of the impact of physical activity in animal models. Exercise in rodents can be performed under voluntary or forced conditions. The former presents the disadvantage that the volume and intensity of exercise varies from subject to subject. On the other hand, a major challenge of the forced training protocol is the low level of performance typically achieved within a given session. Thus, the aim of the present study was to evaluate the effectiveness of gradual increasing of the volume and intensity (training habituation protocol) to improve the locomotor performance in a forced running-wheel system in rats. Sprague-Dawley rats were randomly assigned to either a group that received an exercise training habituation protocol, or a control group. The locomotor performance during forced running was assessed by an incremental exercise test. The experimental results reveal that the total running time and the distance covered by habituated rats was significantly higher than in control ones. We conclude that the exercise habituation protocol improves the locomotor performance in forced running wheels.