M. Bonato

Sleep quality and high intensity interval training at two different times of day: A crossover study on the influence of the chronotype in male collegiate soccer players

ABSTRACT The influence of the chronotype on the sleep quality in male collegiate soccer players in response to acute high intensity interval training (HIIT) performed at two different times of day was evaluated. The sleep quality was poorer in the morning-type than in the evening-type players after the evening HIIT session, whereas no significant changes in the sleep quality of the two chronotypes after the morning HIIT session was observed. The results suggest that an athlete’s chronotype should be taken into account when scheduling training sessions and to promote faster recovery processes.

Effects of a Short-Term High-Nitrate Diet on Exercise Performance

It has been reported that nitrate supplementation can improve exercise performance. Most of the studies have used either beetroot juice or sodium nitrate as a supplement; there is lack of data on the potential ergogenic benefits of an increased dietary nitrate intake from a diet based on fruits and vegetables. Our aim was to assess whether a high-nitrate diet increases nitric oxide bioavailability and to evaluate the effects of this nutritional intervention on exercise performance. Seven healthy male subjects participated in a randomized cross-over study. They were tested before and after 6 days of a high (HND) or control (CD) nitrate diet (~8.2 mmol∙day−1 or ~2.9 mmol∙day−1, respectively). Plasma nitrate and nitrite concentrations were significantly higher in HND (127 ± 64 µM and 350 ± 120 nM, respectively) compared to CD (23 ± 10 µM and 240 ± 100 nM, respectively). In HND (vs. CD) were observed: (a) a significant reduction of oxygen consumption during moderate-intensity constant work-rate cycling exercise (1.178 ± 0.141 vs. 1.269 ± 0.136 L·min−1); (b) a significantly higher total muscle work during fatiguing, intermittent sub-maximal isometric knee extension (357.3 ± 176.1 vs. 253.6 ± 149.0 Nm·s·kg−1); (c) an improved performance in Repeated Sprint Ability test. These findings suggest that a high-nitrate diet could be a feasible and effective strategy to improve exercise performance.

Salivary cortisol concentration after high-intensity interval exercise: Time of day and chronotype effect

ABSTRACT Due to personal and working necessities, the time for exercise is often short, and scheduled early in the morning or late in the afternoon. Cortisol plays a central role in the physiological and behavioral response to a physical challenge and can be considered as an index of exercise stress. Therefore, the aim of this study was to evaluate the influence of the circadian phenotype classification on salivary cortisol concentration in relation to an acute session of high-intensity interval exercise (HIIE) performed at different times of the day. Based on the morningness–eveningness questionnaire, 12 M-types (N = 12; age 21 ± 2 years; height 179 ± 5 cm; body mass 74 ± 12 kg, weekly training volume 8 ± 1 hours) and 11 E-types (N = 11; age 21 ± 2 years; height 181 ± 11 cm; body mass 76 ± 11 kg, weekly training volume 7 ± 2 hours) were enrolled in a randomized crossover study. All subjects underwent measurements of salivary cortisol secretion before (PRE), immediately after (POST), and 15 min (+15 min), 30 min (+30 min), 45 min (+45 min) and 60 min (+60 min) after the completion of both morning (08.00 am) and evening (08.00 p.m.) high-intensity interval exercise. Two-way analysis of variance with Tuckey’s multiple comparisons test showed significant increments over PRE-cortisol concentrations in POSTcondition both in the morning (4.88 ± 1.19 ng · mL−1 vs 6.60 ± 1.86 ng · mL−1, +26.1%, P < 0.0001, d > 0.8) and in the evening (1.56 ± 0.48 ng · mL−1 vs 2.34 ± 0.37, +33.4%, P = 0.034, d > 0.6) exercise in all the 23 subject that performed the morning and the evening HIIE. In addition, during morning exercise, significant differences in cortisol concentration between M-types and E-types at POST (5.49 ± 0.98 ng · mL−1 versus 8.44 ± 1.08 ng · mL−1, +35%, P < 0.0001, d > 0.8), +15 min (4.52 ± 0.42 ng · mL−1 versus 6.61 ± 0.62 ng · mL−1, +31.6%, P < 0.0001, d > 0.8), +30 min (4.10 ± 1.44 ng · mL−1 versus 6.21 ± 1.60 ng · mL−1, +34.0%, P < 0.0001, d = 0.7), + 45 min (3.78 ± 0.55 ng · mL−1 versus 5.80 ± 0.72 ng · mL−1, +34.9%, P < 0.0001, d = 0.7), and + 60 min condition(3.53 ± 0.45 ng · mL−1 versus 5.78 ± 1.13 ng · mL−1, 38.9%, P = 0.0008, d = 0.7) were noted. No statistical significant differences between M-types and E-types during evening HIIE on post-exercise cortisol concentration were detected. E-types showed a higher morning peak of salivary cortisol respect to M-types when performing a HIIE early in the morning and produced higher salivary cortisol concentrations after the cessation of the exercise. Practical applications suggest that it is increasingly important for the exercise professionals to identify the compatibility between time of day for exercising and chronotype to find the individual’s favorable circadian time to perform a HIIE.

Ratings of Perceived Exertion and Self-reported Mood State in Response to High Intensity Interval Training. A Crossover Study on the Effect of Chronotype

The aim of this study was to investigate the influence of chronotype on mood state and ratings of perceived exertion (RPE) before and in response to acute high intensity interval exercise (HIIE) performed at different times of the day. Based on the morningness–eveningness questionnaire, 12 morning-types (M-types; N = 12; age 21 ± 2 years; height 179 ± 5 cm; body mass 74 ± 12 kg) and 11 evening-types (E-types; N = 11; age 21 ± 2 years; height 181 ± 11 cm; body mass 76 ± 11 kg) were enrolled in a randomized crossover study. All subjects underwent measurements of Profile of Mood States (POMS), before (PRE), after 12 (POST12) and 24 h (POST24) the completion of both morning (08.00 am) and evening (08.00 p.m.) training. Additionally, Global Mood Disturbance and Energy Index (EI) were calculated. RPE was obtained PRE and 30 min POST HIIE. Two-way ANOVA with Tukey’s multiple comparisons test of POMS parameters during morning training showed significant differences in fatigue, vigor and EI at PRE and POST24 between M-types and E-types. In addition, significant chronotype differences were found only in POST12 after the evening HIIE for fatigue, vigor and EI. For what concerns Borg perceived exertion, comparing morning versus evening values in PRE condition, a higher RPE was observed in relation to evening training for M-types (P = 0.0107) while E-types showed higher RPE values in the morning (P = 0.008). Finally, intragroup differences showed that E-types had a higher RPE respect to M-types before (P = 0.002) and after 30 min (P = 0.042) the morning session of HIIE. No significant changes during the evening training session were found. In conclusion, chronotype seems to significantly influence fatigue values, perceived exertions and vigor in relation to HIIE performed at different times of the day. Specifically, E-types will meet more of a burden when undertaking a physical task early in the day. Practical results suggest that performing a HIIE at those times of day that do not correspond to subjects’ circadian preference can lead to increased mood disturbances and perceived exertion. Therefore, an athlete’s chronotype should be taken into account when scheduling HIIE. Trial registration: ACTRN12617000432314, registered 24 March 2017, “retrospectively registered”. Web address of trial: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=371862&showOriginal=true&isReview=true

Effects of Manipulating Volume and Intensity Training in Masters Swimmers

PURPOSE Recently, some studies have suggested that overall training intensity may be more important than training volume for improving swimming performance. However, those studies focused on very young subjects, and/or the difference between high-volume and high-intensity training was blurred. The aim of this study was to investigate in masters swimmers the effects of manipulation of training volume and intensity on performance and physiological variables. METHODS A group of 10 male masters swimmers (age 32.3 ± 5.1 y) performed 2 different 6-wk training periods followed by 1 wk of tapering. The first period was characterized by high training volume performed at low intensity (HvLi), whereas the second period was characterized by low training volume performed at high intensity (LvHi). Peak oxygen consumption (VO2peak) during incremental arm exercise, individual anaerobic threshold (IAT), and 100-m, 400-m, and 2000-m-freestyle time were evaluated before and at the end of both training periods. RESULTS HvLi training significant increased VO2peak (11.9% ± 4.9% [mean change ± 90%CL], P = .002) and performance in the 400-m (-2.8% ± 1.8%, P = .002) and 2000-m (-3.4% ± 2.9%, P = .025), with a likely change in IAT (4.9% ± 4.7%, P > .05). After LvHi training, speed at IAT (12.4% ± 5.3%, P = .004) and 100-m performance (-1.2% ± 0.8%, P = .001) also improved, without any significant changes in VO2peak, 2000-m, and 400-m. CONCLUSIONS These findings indicate that in masters swimmers an increase of training volume may lead to an improvement of VO2peak and middle- to long-distance performance. However, a subsequent period of LvHi training maintains previous adjustments and positively affects anaerobic threshold and short-distance performance.

Elite Female Basketball Players' Body-Weight Neuromuscular Training and Performance on the Y-Balance Test

CONTEXT Neuromuscular training enhances unconscious motor responses by stimulating both the afferent signals and central mechanisms responsible for dynamic joint control. Dynamic joint-control training is a vital component of injury-prevention programs. OBJECTIVE To investigate the effects of body-weight neuromuscular training on Y-Balance Test (YBT) performance and postural control in female basketball players. DESIGN Randomized controlled clinical trial. SETTING Basketball practice sessions. PATIENTS OR OTHER PARTICIPANTS A total of 28 healthy elite female basketball players were randomly assigned to an experimental (n = 14) or a control group (n = 14). INTERVENTION(S) Before their regular practice sessions, the experimental group warmed up with body-weight neuromuscular exercises and the control group with standard tactical-technical exercises twice weekly for 8 weeks. MAIN OUTCOME MEASURE(S) Anterior-, posteromedial-, and posterolateral-reach and composite YBT scores were measured before and after 8 weeks of training. RESULTS Improvement over baseline scores was noted in the posteromedial (right = 86.5 ± 4.5 cm versus 89.6 ± 2.2 cm, +3.5%, P = .049; left = 85.5 ± 4.3 cm versus 90.2 ± 2.7 cm, +5.5%, P = .038)- and posterolateral (right = 90.7 ± 3.6 cm versus 94.0 ± 2.7 cm, +3.6%, P = .016; left = 90.9 ± 3.5 cm versus 94.2 ± 2.6 cm, +3.6%, P = .011)-reach directions and in the composite YBT scores (right = 88.6% ± 3.2% versus 94.0% ± 1.8%, +5.4%, P = .0004; left = 89.2% ± 3.2% versus 94.5% ± 3.0%, +5.8%, P = .001) of the experimental group. No differences in anterior reach were detected in either group. Differences were noted in postintervention scores for posteromedial reach (right = 89.6 ± 2.2 cm versus 84.3 ± 4.4 cm, +4.1%, P = .005; left = 94.2 ± 2.6 cm versus 84.8 ± 4.4 cm, +10%, P = .003) and composite scores (right = 94.0% ± 1.8% versus 87.3% ± 2.0%, +7.1%, P = .003; left = 94.8% ± 3.0% versus 87.9% ± 3.4%, +7.3%, P < .0001) between the experimental and control groups. CONCLUSIONS Body-weight neuromuscular training improved postural control and lower limb stability in female basketball players as assessed with the YBT. Incorporating neuromuscular training into the workout routines for basketball players may enhance joint awareness and reduce the risk of lower extremity injury.

A 45-Second Self-Test for Cardiorespiratory Fitness: Heart Rate-Based Estimation in Healthy Individuals

Cardio-respiratory fitness (CRF) is a widespread essential indicator in Sports Science as well as in Sports Medicine. This study aimed to develop and validate a prediction model for CRF based on a 45 second self-test, which can be conducted anywhere. Criterion validity, test re-test study was set up to accomplish our objectives. Data from 81 healthy volunteers (age: 29 ± 8 years, BMI: 24.0 ± 2.9), 18 of whom females, were used to validate this test against gold standard. Nineteen volunteers repeated this test twice in order to evaluate its repeatability. CRF estimation models were developed using heart rate (HR) features extracted from the resting, exercise, and the recovery phase. The most predictive HR feature was the intercept of the linear equation fitting the HR values during the recovery phase normalized for the height2 (r2 = 0.30). The Ruffier-Dickson Index (RDI), which was originally developed for this squat test, showed a negative significant correlation with CRF (r = -0.40), but explained only 15% of the variability in CRF. A multivariate model based on RDI and sex, age and height increased the explained variability up to 53% with a cross validation (CV) error of 0.532 L ∙ min-1 and substantial repeatability (ICC = 0.91). The best predictive multivariate model made use of the linear intercept of HR at the beginning of the recovery normalized for height2 and age2; this had an adjusted r2 = 0. 59, a CV error of 0.495 L·min-1 and substantial repeatability (ICC = 0.93). It also had a higher agreement in classifying CRF levels (κ = 0.42) than RDI-based model (κ = 0.29). In conclusion, this simple 45 s self-test can be used to estimate and classify CRF in healthy individuals with moderate accuracy and large repeatability when HR recovery features are included.

Are the World Junior Championship Finalists for Middle- and Long-Distance Events Currently Competing at International Level?

PURPOSE To analyze how many finalists of the International Association of Athletics Federations (IAAF) World Junior Championships (WJCs) in the middle- and long-distance track events had dropped out from high-level competitions. METHODS Starting from 2002, the 8 male and the 8 female finalists in the middle- and long-distance events of 6 editions of the WJC were followed until 2015 to evaluate how many missed the IAAF rankings for 2 consecutive years starting from the year after WJC participation. For those still competing at elite level, their careers were monitored. RESULTS In 2015, 61% of the 2002, 54.8% of the 2004, 48.3% of the 2006, 37.5% of the 2008, 26.2% of the 2010, and 29% of the 2012 WJC finalists were not present in the IAAF rankings. Of the 368 athletes considered, 75 (20.4%) were able to achieve the IAAF top 10 in 2.4 ± 2.2 y. There is evidence of relationships between dropout and gender (P = .040), WJC edition (P = .000), and nationality (P = .010) and between the possibility to achieve the IAAF top 10 and dropout (P = .000), continent (P = .001), relative age effect (P = .000), and quartile of birth (P = .050). CONCLUSIONS Even if 23 of the finalists won a medal at the Olympic Games or at the World Championships, it is still not clear if participation at the WJC is a prerequisite to success at a senior level.

Neuromuscular training reduces lower limb injuries in elite female basketball players. A cluster randomized controlled trial

The study was a two‐armed, parallel group, cluster randomized controlled trial in which 15 teams (160 players) were assigned to either an experimental group (EG, 8 teams n = 86), which warmed‐up with bodyweight neuromuscular exercises, or a control group (CG, 7 teams, n = 74) that performed standard tactical‐technical exercises before training. All injuries during the 2015‐2016 regular season were counted. Epidemiologic incidence proportion and incidence rate were also calculated. Countermovement jump (CMJ) and composite Y‐Excursion Balance test (YBT) were used to assess lower limb strength and postural control. A total of 111 injuries were recorded. Chi‐square test detected statistically significant differences between EG and CG (32 vs 79, P = .006). Significant differences in the injuries sustained in the EG (21 vs 11, P = .024) and CG (52 vs 27, P = .0001) during training and matches, respectively, were observed. Significant differences in post‐intervention injuries were observed between in EG and CG during training (21 vs 52, P < .0001) and matches (11 vs 27, P = .006). Significant differences in epidemiologic incidence (0.37 vs 1.07, P = .023) and incidence rate (1.66 vs 4.69, P = .012) between the EG and the CG were found. Significant improvement in CMJ (+9.4%, P < .0001; d = 1.2) and composite YBT (right: +4.4%, P = .001, d = 1.0; left: +3.0%, P = .003; d = 0.8) for the EG was noted. Significant differences in post‐intervention CMJ (+5.9%, P = .004) and composite YBT scores (right, +3.7%, P = .012; left, +2.3%, P = .007) between the EG and the CG were observed. Including bodyweight neuromuscular training into warm‐up routines reduced the incidence of serious lower limb injuries in elite female basketball players.

Effect of repeated-sprints on the reliability of short-term parasympathetic reactivation

This study determined the reliability of post-exercise heart rate recovery (HRR) and vagal-related HR variability (HRV) after repeated-sprints (RSs), and contrasted it with the smallest worthwhile change (SWC) of these indices. Fourteen healthy male participants performed on four occasions, separated by 7 days, five 30-m sprints interspersed by 25-s of recovery. Post-exercise HR during 10 min of seated rest was measured. HRR during the first 60-s of recovery was computed (HRR60s). HRV indices were calculated in time and frequency domains during the last 5-min of the recovery. Absolute and relative reliability were assessed by typical error of measurement expressed as coefficient of variation (CV) and intraclass correlation coefficients (ICCs), respectively. Sensitivity was assessed comparing SWC to the typical error of measurement. CV ranged from 3.6% to 13.5% and from 6.3% to 109.2% for the HRR and HRV indices, respectively. ICCs were from 0.78 to 0.96 and from 0.76 to 0.92, respectively. HRR and HRV indices showed large discrepancies reliability. HRR60s and the square root of the mean sum of the squared differences between R-R intervals presented the highest levels of both absolute and relative reliability. However, SWC was lower than the typical error of measurement, indicating insufficient sensitivity to confidently detect small, but meaningful, changes in HRR and HRV indices.