Individually guided training prescription by heart rate variability and self-reported measure of stress tolerance in recreational runners: Effects on endurance performance

The aim of this study was to determine the effect of endurance training individually guided by objective (Heart Rate Variability-HRV) or self-report measure of stress (DALDA-questionnaire) in comparison to predefined endurance training prescription for improving endurance performance in recreational runners. After a 2-week preliminary baseline period to establish resting HRV and self-reported measure of stress, thirty-six male recreational runners were randomly assigned to HRV-guided (G_HRV; n = 12), DALDA-guided (G_D; n = 12) or predefined training (G_T; n = 12) prescription groups. Before and after 5-weeks of endurance training, participants performed a track field peak velocity (V_{peak_TF}), time limit (T_lim) at 100% of V_{peak_TF} and 5 km time-trial (5 km TT) tests. G_D lead to higher improvements in V_{peak_TF} (8.4 ± 1.8%; ES = 1.41) and 5 km TT (-12.8 ± 4.2%; ES = -1.97), than G_HRV (6.6 ± 1.5% and -8.3 ± 2.8%; ES = -1.20; 1.24) and G_T (4.9 ± 1.5% and -6.0 ± 3.3%; ES = -0.82; 0.68), respectively, with no differences for T_lim. Self-report measures of stress may be used to individualize endurance training prescription on a daily basis leading to better performance enhancement, which may be used with HRV for a holistic understanding of daily training-induce adaptations.

Effects of photobiomodulation and deep water running in patients with chronic non-specific low back pain: a randomized controlled trial

Photobiomodulation therapy (PBM) is often used to treat musculoskeletal disorders such as chronic non-specific low back pain (NSCLBP) as it can have positive effects on biomarkers-creatine kinase (CK) and serum cortisol levels-related to stress caused by physical exercise, such as deep water running (DWR) or by pain. The aim of this study was to evaluate the effects of the combination of PBM and aquatic exercise (DWR) on the intensity of pain, disability, 6-min walk test adapted (6WTA), and on cortisol and creatine kinase (CK) levels in a population with NSCLBP. The participants were allocated into three groups: TG_PBM (Photobiomodulation and Training Group), TG_PLA (Placebo Photobiomodulation and Training Group), and the G_PBM (Photobiomodulation Group). Information regarding anthropometric data, blood pressure, and heart rate were collected, and the questionnaires were applied: IPAQ-Short Form, Oswestry Disability Index, and the Visual Analog Scale for Pain. The submaximal exercise test (6WTA) was performed. Blood was collected for analysis of cortisol and CK levels. The training sessions were performed twice a week, for 4 weeks. In the intragroup comparisons, there were statistically significant changes in the TG_PBM and G_PBM groups in the outcomes pain intensity, disability (reductions in both groups), and in cortisol (increased in the TG_PBM and reduced in the G_PBM); in the TG_PLA group, there was a statistically significant reduction only in the outcome of pain intensity. In the intergroup comparison, in the comparison between TG_PBM and TG_PLA, there was a statistically significant difference in the level of cortisol, as well as in the comparison between TG_PBM and G_PBM, in which there was a statistically significant difference for this same outcome (cortisol) and for the 6WTA outcome. The effects of the combination of PBM and aquatic exercise have positive effects on reducing pain intensity, disability, and cortisol levels, but its effects on other variables (6WTA and CK) are too small to be considered significant. Trial registration number: NCT03465228-April 3, 2019; retrospectively registered (ClinicalTrials.gov).

Reliability of Peak Running Velocity Obtained on the Track Field in Runners of Different Performance Levels

The aim of this study was to verify the reliability of peak running velocity obtained on the track field (V_{peak_TF}) in runners of different performance levels. 39 male endurance runners were divided into two groups: trained runners (TR; n = 22; 10-km time running performance of 35.2 ± 1.7 min), and recreational runners (RR; n = 17; 10-km time running performance of 51.3 ± 4.8 min). They performed three maximal incremental running tests on the official track field (400 m), with an interval of 1 week between trials to determine the reliability of V_{peak_T}. The V_{peak_TF} showed high reliability, presenting an intraclass correlation coefficient and coefficient of variation of 0.97 and 1.28%, and 0.90 and 1.24% for TR and RR, respectively. Both TR and RR showed lowest bias and limits of agreement between test and retest (V_{peak_TF1} and V_{peak_TF2}). In addition, there was no statistical test-retest difference for V_{peak_TF}. In addition, the HR and RPE submaximal values were reliable for both TR and RR. Therefore, the V_{peak_TF} showed high reliability in both TR and RR. These findings reinforce that the protocol for determining V_{peak_TF}, using increments of 1 km h^–1 every 3 min is reliable regardless of the performance level of the runners.

Peak Running Velocity or Critical Speed Under Field Conditions: Which Best Predicts 5-km Running Performance in Recreational Runners?

This study aimed to examine which variable, between the peak running velocity determined on the track field (V_{peak_TF}) and critical speed (CS), is the best predictor of the 5-km running performance in recreational runners. Twenty-five males performed three tests to determine the V_{peak_TF}, CS, and 5-km running performance on the track field, with a minimal interval of 48 h between each test. The V_{peak_TF} protocol started with a velocity of 8 km⋅h^–1, followed by an increase of 1 km⋅h^–1 every 3 min until volitional exhaustion, which was controlled by sound signals, with cones at every 25 m indicating when the participants were required to pass the cone’s position to maintain the required velocity. The participants performed three time trials (TTs) (1: 2,600 m; 2: 1,800 m; and 3: 1,000 m) on the same day, with a 30-min rest period to determine the CS through the combinations of three (CS₁,₂,₃) and two TTs (CS₁,₂, CS₁,₃, and CS₂,₃). The 5-km running performance time was recorded to determine the test duration, and the mean velocity (MV) was calculated. There was a significant difference observed between the V_{peak_TF} and the MV 5-km running performance. However, no differences were found between the CS values and the MV 5-km running performance. A correlation was observed between the V_{peak_TF} (R = −0.90), CS₁,₂,₃ (R = −0.95), CS₁,₃ (R = −0.95), and the 5-km running performance time. Linear regression indicated that the V_{peak_TF} (R² = 0.82), CS₁,₂,₃ (R² = 0.90), and CS₁,₃ (R² = 0.90) significantly predicted the 5-km running performance time. The CS results showed a higher predictive power for the 5-km running performance, slightly better than the V_{peak_TF}. Also, CS₁,₂,₃ and the CS₁,₃ presented the highest predictive power for the 5-km running performance of recreational runners.

Capsaicin Analogue Supplementation Does Not Improve 10 km Running Time-Trial Performance in Male Amateur Athletes: A Randomized, Crossover, Double-Blind and Placebo-Controlled Study

Background: To investigate the acute effects of a capsaicin analogue supplement on 10 km time-trial performance and physiological responses in amateur athletes. Methods: Twenty-one participants (age = 29.3 ± 5.5 years, weight 74.2 ± 11.3 kg, height 176.0 ± 0.0 cm, fat mass 12.7 ± 3.8%, V˙O_2max 62.7 ± 8.4 mL·k⁻¹·min⁻¹), completed two randomized, double-blind trials: capsaicin analogue condition (Capsiate (CAP) = 24 mg) or a placebo (PLA) condition. The participants consumed two doses of 12 mg of CAP or PLA capsule 45 min before and immediately at the start of each trial. The time required to complete 10 km, lactate concentration, maximum heart rate (HR_peak), and rating of perceived exertion (RPE) were recorded. Results: The 10 km time-trial performance (CAP = 45.07 ± 6.41 min vs. PLA = 45.13 ± 6.73, p = 0.828) was not statistically significantly different between conditions. No statistically significant differences between conditions were detected for lactate concentration (p = 0.507), HR_peak (p = 0.897) and RPE (p = 0.517). Conclusion: Two doses of a 12 mg Capsaicin analogue supplement did not improve performance and physiological responses in a 10 km running time-trial in amateur athletes.

Does Previous Application of Photobiomodulation Using Light-Emitting Diodes at Different Energy Doses Modify the Peak Running Velocity and Physiological Parameters? A Randomized, Crossover, Double-Blind, and Placebo-Controlled Study

Objective: This study aimed to verify the acute effects of photobiomodulation (PBM) using different doses of LED on peak running velocity (V_peak) and physiological parameters. Materials and methods: The study had a randomized, crossover, double-blind, and placebo-controlled format, in which 15 physically active males were submitted, besides the control (CON), to four conditions performed 5 min before the maximal incremental treadmill tests for the determination of V_peak: placebo (PLA) and three conditions of PBM application at different doses: PBM applied with 30 J per area (PBM₁), PBM applied with 120 J per area (PBM₂), and PBM applied with 180 J per area (PBM₃). The LED was applied using an equipment with 56 diodes of red light (660 nm; 50 mW/cm² and 1.5 J/cm² each diode) and 48 diodes of infrared light (850 nm; 150 mW/cm² and 4.5 J/cm² each diode). The PBM was applied in two regions of the quadriceps muscle, two regions of the femoral biceps muscle, and one region of the gastrocnemius muscle in both legs. Results: There was no difference among the outcomes from PBM irradiations and PLA condition for the variables, V_peak (CON = 13.4 ± 1.6; PLA = 13.4 ± 1.6; PBM₁ = 13.5 ± 1.7; PBM₂ = 13.4 ± 1.6; PBM₃ = 13.4 ± 1.7 km/h), similar to other variables associated with aerobic running performance analyzed during the maximal incremental treadmill tests for V_peak determination: lactate peak, heart rate, and rating of perceived exertion. Conclusions: We concluded that the application of different doses of PBM using LEDs did not modify V_peak and physiological and perceptual parameters.

Effects of Endurance Running Training Associated With Photobiomodulation on 5-Km Performance and Muscle Soreness: A Randomized Placebo-Controlled Trial

This study aimed to investigate the influence of endurance running training associated with PBM on endurance performance variables and muscle soreness in untrained men. Thirty untrained men were distributed randomly into a placebo (PLA) group and photobiomodulation group (PBMG) and they performed 8 weeks of running training. The PBMG had the PBM performed before all training sessions. The PBM was applied using LED equipment with 56 diodes of red light (660 nm) and 48 diodes of infrared light (850 nm). The application was performed in 5 points per leg, with a dose of 60 J at each point and a total energy delivered per leg of 300 J. Peak running velocity, time limit tests and 5-km performance were assessed pre and post-training; muscle soreness was evaluated before all training sessions. The V_peak increased and 5-km running time (t_5–km) decreased (P < 0.001) in both groups. In addition, the magnitude based-inference analysis showed a possibly positive effect on V_peak and t_5–km and for PBMG compared to PLA group. Furthermore, there was a moderate ES of 0.82 on attenuation in muscle soreness in the third week of endurance running training. Therefore, although the magnitude-based inference analysis demonstrated a possibly positive effect on V_peak and t_5–km and for PBMG compared to PLA group and a moderate ES on attenuation in muscle soreness in the last weeks of endurance running training, no significant difference were found between PBMG and PLA interventions.

Photobiomodulation by Led Does Not Alter Muscle Recovery Indicators and Presents Similar Outcomes to Cold-Water Immersion and Active Recovery

Purpose: The aim of the present study was to investigate the effectiveness of photobiomodulation therapy (PBMT) on muscle recovery based on inflammation (interleukin-10 [IL-10]; tumor necrosis factor-α [TNFα]), muscle damage markers (creatine kinase [CK]; lactate dehydrogenase [LDH]), delay onset muscle soreness (DOMS), and countermovement jump performance (CMJ) after two sprint interval training (SIT) sessions compared with a placebo condition (part-I), as well as to compare the effectiveness of PBMT with active recovery (AR) and cold-water immersion (CWI) (part-II). Methods: Part-I was conducted as a double-blind, randomized and placebo-controlled study and part-II as a parallel-group study. Thirty-six men participated in the studies (12 participants in part-I and 36 participants in part-II). Volunteers performed two SITs interspaced by 24-h (SIT₁ and SIT₂) to mimic the effect of accumulating 2 consecutive days of SIT. In part-I, only after SIT₂, PBMT [Total energy: 600J (300J per leg in 5 spots); wavelength: 660-850 nm] or placebo interventions were performed, while in part-II PBMT (part-I data), AR (15-min; 50% of the maximal aerobic power), or CWI (10-min; 10°C) were carried out, also after SIT₂. Blood samples were collected before (i.e., baseline), and 0.5, 1, 24, 48, and 72-h after SIT₂, while CMJ and DOMS were measured before, 24, 48, and 72-h after SIT₂. Results: In part-I, there were no interactions between PBMT and placebo conditions for any blood markers (P ≥ 0.313), DOMS (P = 0.052), and CMJ (P = 0.295). However, an effect of time was found with increases in LDH, CK, and IL-10 (P ≤ 0.043) as well as a decrease in DOMS at 72-h compared with 24-h (P = 0.012). In part-II, there were no interactions between the PBMT, AR, and CWI groups for any markers at the same moments (P ≥ 0.189) and for the peak and integral values (P ≥ 0.193), for DOMS (P = 0.314) and CMJ (P = 0.264). However, an effect of time was found with an increase in CK and IL-10 (P = 0.003), while DOMS decreased at 48 and 72-h compared with 24-h (P = 0.001). Conclusion: In summary, PBMT had no effect on inflammation, muscle damage, CMJ performance, or DOMS after two consecutive sprint interval training sessions compared to placebo, CWI, and AR strategies.

Effect of beetroot juice supplementation on 10-km performance in recreational runners

The purpose of this study was to investigate the effects of chronic beetroot juice (BRJ) supplementation on 10-km running performance in recreational runners. In a double-blind, placebo-controlled, crossover-designed study, 14 male recreational runners (age, 27.8 ± 3.4 years) performed three 10-km running tests, at baseline and under the conditions of BRJ supplementation and placebo (PLA). Supplementation was administered for 3 days, and on the days of the assessments, the ingestion occurred 2 h before the test and consisted of a dose of 420 mL of BRJ in natura (8.4 mmol inorganic nitrate (NO3−)·day−1) or PLA with depleted NO3− (0.01 mmol NO3−·day−1). The mean velocity (MV) was calculated, and the following variables were determined: maximal heart rate, maximal rating of perceived exertion, blood glucose concentration (analyzed before and after the test), and lactate peak. There was no main effect between conditions regarding 10-km running time performance (BRJ: 50.1 ± 5.3 min; PLA: 51.0 ± 5.1 min; P = 0.391) and total MV (BRJ: 12.1 ± 1.3 km·h−1; PLA: 11.9 ± 1.2 km·h−1; P = 0.321) or in the other analyzed variables. The time to complete the first half of the test (5 km) was statistically lower in the BRJ group than in the PLA group (P = 0.027). In conclusion, chronic supplementation with BRJ increased MV in the first half of the test and improved the final test times of 10 of the 14 runners, although we did not find a statistically significant difference in the performance of the 10-km run.

LED session prior incremental step test enhance VO2max in running

This study aimed to investigate the effect of prior LED sessions on the responses of cardiorespiratory parameters during the running incremental step test. Twenty-six healthy, physically active, young men, aged between 20 and 30 years, took part in this study. Participants performed two incremental load tests after placebo (PLA) and light-emitting diode application (LED), and had their gas exchange, heart rate (HR), blood lactate, and rating of perceived exertion (RPE) monitored during all tests. The PLA and LED conditions were compared using the dependent Student t test with significance set at 5%. The T test showed higher maximum oxygen uptake (VO_2max) (PLA = 47.2 ± 5.7; LED = 48.0 ± 5.4 ml kg^-1 min^-1, trivial effect size), peak velocity (V_peak) (PLA = 13.4 ± 1.2; LED = 13.6 ± 1.2 km h^-1, trivial effect size), and lower maximum HR (PLA = 195.3 ± 3.4; LED = 193.3 ± 3.9 b min^-1, moderate effect size) for LED compared to PLA conditions. Furthermore, submaximal values of HR and RPE were lower, and submaximal VO₂ values were higher when LED sessions prior to the incremental step test were applied. A positive response of the previous LED application in the blood lactate disappearance was also demonstrated, especially 13 and 15 min after the test. It is concluded that LED sessions prior to exercise modify cardiorespiratory response by affecting running tolerance during the incremental step test, metabolite clearance, and RPE. Therefore, LED could be used as a prior exercise strategy to modulate oxidative response acutely in targeted muscle and enhance exercise tolerance.

Peak velocity and its time limit are as good as the velocity associated with VO 2max for training prescription in runners

This study compared the effects of 4 weeks of training prescribed by peak velocity (V _peak ) or velocity associated with maximum oxygen uptake (vVO _2max ) in moderately trained endurance runners. Study participants were 14 runners (18–35 years) randomized into 2 groups, named group VO ₂ (GVO ₂ ) and group V _peak (GVP). The GVO ₂ had training prescribed by vVO _2max and its time limit (t _lim ), whereas the GVP had training prescribed by V _peak and its t _lim . Four tests were performed on a treadmill: 2 maximum incremental for V _peak and vVO _2max and 2 for their t _lim . Performance (10 km) was evaluated on a 400 m track. Evaluations were repeated after 4 weeks of endurance training. The results showed a significant effect of training on V _peak [GVP (16.7±1.2 – 17.6±1.5 km ^. h ⁻¹ ), GVO ₂ (17.1±1.9–17.7±1.6 km·h ⁻¹ )]; vVO _2max [GVP (16.4±1.4–17.0±1.3 km·h ⁻¹ ), GVO ₂ (17.2±1.7–17.5±1.9 km·h ⁻¹ )]; and 10 km performance [GVP (41.3±2.4–39.9±2.7 min), GVO ₂ (40.1±3.4–39.2±2.9 min)]. The V _peak highly correlated with performance in both pre- and post-training in GVP (–0.97;–0.86) and GVO ₂ (–0.95;–0.94), as well as with vVO _2max in GVP (–0.82;–0.88) and GVO ₂ (–0.99; –0.98). It is concluded that training prescribed by V _peak promoted similar improvements compared to training prescribed by vVO _2max . The use of V _peak is recommended due to its practical application and the low cost of determination.

The influence of the regression model and final speed criteria on the reliability of lactate threshold determined by the Dmax method in endurance-trained runners

Few studies verified the reliability of the lactate threshold determined by Dmax method (LT_Dmax) in runners and it remains unclear the effect of the regression model and the final speed on the reliability of LT_Dmax. This study aimed to examine the test-retest reliability of the speed at LT_Dmax in runners, considering the effects of the regression models (exponential-plus-constant vs third-order polynomial) and final speed criteria (complete vs proportional). Seventeen male, recreational runners performed 2 identical incremental exercise tests, with increments of 1 km·h^-1 each for 3 min on treadmill to determine peak treadmill speed (V_peak) and lactate threshold. Earlobe capillary blood samples were collected during rest between the stages. The V_peak was defined as the speed of the last complete stage (complete final speed criterion) and as the speed of the last complete stage added to the fraction of the incomplete stage (proportional final speed criterion). Lactate threshold was determined from exponential-plus-constant and from third-order polynomial regression models with both complete and proportional final speed criteria and from fixed blood lactate level of 3.5 mmol·L^-1 (LT_3.5mM). The LT_Dmax obtained from the exponential-plus-constant regression model presented higher reliability (coefficient of variation (CV) ≤ 3.7%) than the LT_Dmax calculated from the third-order polynomial regression model (CV ≤ 5.8%) and LT_3.5mM (CV = 5.4%). The proportional final speed criterion is more appropriate when using the exponential-plus-constant regression model, but less appropriate when using the third-order polynomial regression model. In conclusion, exponential-plus-constant using the proportional final speed criterion is preferred over LT_3.5mM and over third-order polynomial regression model to determine a reliable LT_Dmax.

Relationship between heart rate deflection point determined by Dmax method and 10-km running performance in endurance recreationally-trained female runners

AIM

The aim of this paper was to verify the relationship between the speed at heart rate deflection point based on Dmax method (sHRDPDmax) with 10-km running performance and the speed at lactate threshold calculated with Dmax method (sLTDmax) in endurance recreationally-trained female runners. We also aim to examine the influence of exponential-plus-constant and third-order polynomial regression models and the influence of the heart rate points (model with initial HR points above 140 b·min(-1) versus model with all HR points) on the determination of the sHRDPDmax.

METHODS

Thirteen endurance recreationally-trained female runners were recruited. Participants performed a discontinuous incremental exercise tests initiating at 7 km·h(-1) with 1 km·h(-1) increments each 3 min to determine sHRDPDmax and sLTDmax according to two adjustments: 1) exponential-plus-constant regression model (sHRDPexp and sLTexp); 2) third-order polynomial regression model (sHRDPpol and sLTpol). The sHRDPDmax was also calculated based on HR points above 140 b·min(-1) (sHRDPexp>140 and sHRDPpol>140). Each participant performed a 10-km running performance (s10km).

RESULTS

Only the sHRDPexp and sHRDPexp>140 correlated with s10km (sHRDPexp, r=0.87; sHRDPexp>140, r=0.76) and showed higher correlations than the sHRDPpol and sHRDPpol>140 with sLTDmax. The sHRDPexp presented higher correlation with sLTexp than sHRDPexp>140, however sHRDPexp>140 better correlated with sLTpol than sHRDPexp. Furthermore, sHRDPpol>140 demonstrated higher correlations with sLTexp and sLTpol than sHRDPpol.

CONCLUSION

The determination of sHRDPDmax according to different initial HR point and its correlation with sLTDmax is influenced by the regression model. Further, only sHRDPexp and sHRDPexp>140 were predictors of endurance performance. However, despite the high correlations, the deflection point very often occurred around the midpoint between initial and final speeds during the incremental test suggesting that the exponential-plus-constant may not be an appropriate regression curve.

Evaluation of the Best-designed Graded Exercise Test to Assess Peak Treadmill Speed

This study examined the influence of different speed increments during treadmill exercise tests on peak treadmill speed (Vpeak) and its relationship with a 1-h treadmill running performance. 18 male recreational and amateur runners (10-km running pace: 10-15 km·h(-1)) performed, in an alternate order, 3 continuous incremental exercise tests with different speed increments (0.5, 1.0 and 2.0 km·h(-1)) on a motorized treadmill to determine Vpeak. Thereafter they undertook a 1-h time trial on a treadmill. Vpeak was determined as either (a) the highest speed that could be maintained for a complete minute (Vpeak-60 s), (b) the speed of the last complete stage (Vpeak-C), or (c) the speed of the last complete stage added to the product of the speed increment and the completed fraction of the incomplete stage (Vpeak-P). The Vpeak values were highly influenced by the different speed-incremented rates and the Vpeak-P determined during the protocol comprising speed increments of 1 km·h(-1) presented the highest correlation with 1-h time trial performance (r=0.89). The results suggest that a protocol with speed increments comprising 1 km·h(-1) and with a 3-min stage duration should be used as standard for the determination of Vpeak to assess aerobic fitness and predict endurance performance in recreational runners. Furthermore, the Vpeak-P should be used for the determination of Vpeak.

Comparação entre os métodos direto e indireto de determinação do VO 2máx de praticantes de corrida

INTRODUÇÃO: testes diretos são considerados "padrão ouro" para determinar variáveis fisiológicas, porém o seu custo financeiro é elevado e há a necessidade de mão de obra especializada para sua operacionalização. Sendo assim, os testes indiretos são utilizados pela maioria dos profissionais de Educação Física como uma alternativa acessível à falta da medida direta.OBJETIVO: comparar os valores de consumo máximo de oxigênio (VO2máx) determinados diretamente por um sistema de espirometria com valores determinados a partir de protocolos indiretos.MÉTODOS: participaram 15 pessoas do gênero masculino (27,4 ± 3,5 anos), fisicamente ativas, que realizaram o teste incremental em esteira rolante para determinação direta do VO2máxcom analisador de gases. Os testes para predição do VO2máxforam: ErgoPC; Polar Fitness Test; testes do banco e de Cooper. Foi utilizada a estatística descritiva (média ± desvio padrão - DP); a esfericidade foi testada pelo teste de Mauchly, os métodos foram comparados por ANOVA de medidas repetidas com o ajuste de Bonferroni para comparações múltiplas. A normalidade dos dados foi aferida pelo teste de Shapiro-Wilk e também foi aplicado o teste coeficiente de correlação de Pearson, adotando-se p<0,05.RESULTADOS: o valor médio de VO2máxdireto foi de 55,8 ± 6,1 ml•kg-1•min-1 e os valores para os testes indiretos, percentual de subestimação e coeficiente de correlação, foram, respectivamente: ErgoPc 33,7 ± 4,5 ml•kg-1•min-1 (39,6%; r = 0,71; p<0,001); Polar Fitness Test53,2 ± 6,4 ml•kg-1•min-1 (4,6%; r = 0,64; p = 0,774); teste do banco 48,8 ± 6,3 ml•kg-1•min-1 (12,5%; r = 0,60; P=0,001) e de Cooper 43,9 ± 7,9 ml•kg-1•min-1 (21,4%; r = 0,65; p<0,001).CONCLUSÃO: os métodos indiretos podem sugerir sobrecarga de treino inferior ou superior para adaptações fisiológicas pretendidas por subestimarem o direto, sendo o Polar Fitness Test o mais indicado para uso diário, pois apresentou valores mais próximos ao valor direto.

Reliability of peak running speeds obtained from different incremental treadmill protocols

This study compared the values and reliability of peak running speeds from incremental treadmill protocols with different speed increments. Thirty-one men, recreational, endurance-trained runners performed, in an alternate order, three continuous tests with different speed increments (0.5, 1 and 2 km · h(-1)). The tests were repeated using the same order. Peak speed was identified as (1) the greatest speed that could be maintained for a complete minute (Vpeak-60s), (2) the speed of the last complete stage (Vpeak-C) and (3) the speed of the last complete stage added to the product of the speed increment and the completed fraction of the incomplete stage (Vpeak-P). The Vpeak-P was the most reliable, independent of the incremental test protocol (1.5% ≤ CV ≤ 1.8%), and differently from Vpeak-C (1.8% ≤ CV ≤ 2.6%) and Vpeak-60s (1.6% ≤ CV ≤ 3.8%), the Vpeak-P was only slightly influenced by the incremental test protocol. The results suggest that Vpeak-P should be used to assess aerobic capability and monitor training effects and that other determinations of peak speed should be avoided.

An evaluation of immune system cell infiltrate in the cervical stroma of patients with grade III cervical intraepithelial neoplasia after treatment with intralesional alpha-2B interferon

The aim of this study was to characterize infiltrating immune cells in cervical stroma biopsy samples from patients diagnosed with cervical intraepithelial neoplasias (CINs) who were treated with IFN-alpha 2b. The authors studied 13 volunteers who were diagnosed with Cervical intraepithelial neoplasia CIN II or III and who received intra-lesional treatment with IFN-alpha 2b. They collected pre- and post-treatment biopsies from each patient. They also examined the slides under a common optical microscope with a X400 lens for biopsy sample sections that were labeled with immunohistochemistry for T lymphocyte, B lymphocyte, natural killer cell, macrophage, iNOS, and perforin markers. The presence of immune response cells in the lesion was observed after treatment with intralesional IFN-alpha 2b in patients with CIN II/III changes, a reduction in CD4+ and CD8+ T lymphocyte infiltration in the women who responded well to treatment. However, there was a significant increase in these markers in samples from women who did not respond to treatment. Nonetheless, immunotherapy with IFN-alpha 2b administered intralesionally in patients with CIN II/III yields favorable results in patients who do not smoke.

Gender and distance influence performance predictors in young swimmers

Predictors of performance in adult swimmers are constantly changing during youth especially because the training routine begins even before puberty in the modality. Therefore this study aimed to determine the group of parameters that best predict short and middle swimming distance performances of young swimmers of both genders. Thirty-three 10-to 16-years-old male and female competitive swimmers participated in the study. Multiple linear regression (MLR) was used considering mean speed of maximum 100, 200 and 400 m efforts as dependent variables, and five parameters groups as possible predictors (anthropometry, body composition, physiological and biomechanical parameters, chronological age/pubic hair). The main results revealed explanatory powers of almost 100% for both genders and all performances, but with different predictors entered in MLR models of each parameter group or all variables. Thus, there are considerable differences in short and middle swimming distance, and males and females predictors that should be considered in training programs.

Longitudinal changes in cardiac autonomic function and aerobic fitness indices in endurance runners: a case study with a high-level team

To determine the effects of preparatory phase training on aerobic parameters, resting heart rate variability (HRV) and 5-km performance of high-level endurance runners and the relationship between the percentage change (% change) of resting HRV with the % change of aerobic parameters and 5-km performance. Six runners were assessed before and after seven weeks of training. The aerobic parameters were determined in an incremental test. The HRV was assessed by a heart rate monitor. Athletes performed a 5-km running test in a track. The analysis revealed 'likely' and 'very likely' improvements for velocity associated with maximal oxygen uptake ([Formula: see text]O2max) (20.0±1.0 km·h(-1) to 21.2±0.6 km·h(-1)) and 5-km performance (18.0±0.4 km·h(-1) to 18.9±0.7 km·h(-1)), respectively, as well as 'likely' decrease in high frequency (41.4±18.5 nu to 30.4±14.3 nu), and increase in low frequency (58.5±18.5 nu to 69.6±14.3 nu) band densities. The variation in the velocity associated with [Formula: see text]O2max showed the highest correlation with 5-km performance (r=0.95). The % change in the square root of the mean sum of the squared differences between R-R intervals and standard deviation 1 were highly correlated with variation in 5-km performance (r=0.69 and 0.66). Changes in the velocity associated with [Formula: see text]O2max and vagally mediated HRV were highly associated with 5-km running performance within the investigated team. These results have important implications because these parameters can be assessed longitudinally to monitor adaptation to training.

Predição da potência aeróbia (VO2máx) de crianças e adolescentes em teste incremental na esteira rolante

O consumo máximo de oxigênio (VO2máx) é a quantidade máxima de energia que pode ser produzida pelo metabolismo aeróbio em determinada unidade de tempo, podendo ser determinado direta ou indiretamente através de equações preditivas. O objetivo deste trabalho foi elaborar uma equação preditiva específica para determinar o VO2máx de meninos de 10 a 16 anos. Quarenta e dois meninos realizaram teste ergoespirométrico de corrida em esteira rolante com velocidade inicial de 9 km/h até exaustão voluntária. Através da regressão linear múltipla foi possível desenvolver a seguinte equação para a determinação indireta do VO2máx: VO2máx (ml/min) = -1574,06 + (141,38 x Vpico) + (48,34 * Massa corporal), com erro padrão de estimativa = 191,5 ml/min (4,10 ml/kg/min) e o coeficiente de determinação = 0,934. Sugerimos que esta é uma fórmula adequada para predizer o VO2máx para esta população.

Influence of regression model and incremental test protocol on the relationship between lactate threshold using the maximal-deviation method and performance in female runners

This study examined the influence of the regression model and initial intensity of an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and the endurance performance. Sixteen non-competitive, recreational female runners performed a discontinuous incremental treadmill test. The initial speed was set at 7 km · h⁻¹, and increased every 3 min by 1 km · h⁻¹ with a 30-s rest between the stages used for earlobe capillary blood sample collection. Lactate-speed data were fitted by an exponential-plus-constant and a third-order polynomial equation. The lactate threshold was determined for both regression equations, using all the coordinates, excluding the first and excluding the first and second initial points. Mean speed of a 10-km road race was the performance index (3.04 ± 0.22 m · s⁻¹). The exponentially-derived lactate threshold had a higher correlation (0.98 ≤ r ≤ 0.99) and smaller standard error of estimate (SEE) (0.04 ≤ SEE ≤ 0.05 m · s⁻¹) with performance than the polynomially-derived equivalent (0.83 ≤ r ≤ 0.89; 0.10 ≤ SEE ≤ 0.13 m · s⁻¹). The exponential lactate threshold was greater than the polynomial equivalent (P < 0.05). The results suggest that the exponential lactate threshold is a valid performance index that is independent of the initial intensity of the incremental test and better than the polynomial equivalent.

Comparação entre dois métodos objetivos e individuais de determinação da velocidade de corrida no limiar de lactato

O objetivo deste estudo foi comparar as velocidades de corrida no limiar de lactato (vLL) determinadas pelos métodos objetivos e individuais Dmax (vLL Dmax) e log-log (vLLlog-log) sendo esperado uma relação entre eles melhor do que a relação deles com o método de concentração fixa de lactato sanguíneo em 3,5 mM (vLL3,5mM). Participaram deste estudo 17 corredoras recreacionais com experiência em provas de rua de 10 km (idade: 42,1 ± 6,7 anos; estatura: 1,63 ± 0,03 m; massa corporal 57,2 ± 4,9 kg) que realizaram um teste incremental em esteira ergométrica, com velocidade inicial de 7 km/h e incrementos de 1 km/h a cada três minutos. Amostras de sangue foram coletadas nas pausas de 30 segundos entre cada estágio. As vLL foram 10,3 ± 1,4 (vLLlog-log), 10,9 ± 0,8 (vLL Dmax) e 11,6 ± 1,2 km/h (vLL3,5mM) sendo a vLL3,5mM significantemente superior à vLLlog-log (P <0,001) e à vLL Dmax (P = 0,024). Apesar disso, a amplitude dos limites de concordância (±1,96 DP) entre as vLL foi semelhante, variando entre ±1,48 e ±1,77 km/h e a correlação entre a vLL3,5mM e as velocidades vLLlog-log (r = 0,70) e vLL Dmax (r = 0,78) foi maior que a correlação daquelas velocidades entre si (r = 0,65). Em suma, as velocidades vLLlog-log e vLL Dmax não apresentaram uma melhor relação entre si do que a relação delas com a vLL3,5mM.

Immune response and immunotherapy in intraepithelial and invasive lesions of the uterine cervix

Infection with the human papillomavirus virus (HPV) induces innate and acquired immune responses in the cervical stroma, which are a delicate, balanced and generally unpredictable immunological defense. Because of the immunological breaks that the HPV virus causes, eradication of infected cells does not occur, potentially leading to development of intraepithelial and invasive lesions. Advances in our understanding of the immune system and in the definition of antigens in tumor cells has led to many new treatment strategies. As a result, immunotherapy has the potential to be the most specific treatment for tumors, and one that requires elaboration. Recently, immunotherapy with interferon and dendritc cells has been used on intrapepithelial and invasive cervical lesions with promising results.

Comparação entre os ajustes de curva exponencial e polinomial na determinação do limiar de lactato pelo método Dmax

Comparou-se a velocidade de corrida no limiar de lactato (vLL) determinada pelo método Dmax utilizando-se os ajustes de curva exponencial mais constante (vLLexp) e polinomial de terceira ordem (vLLpol). Dezessete corredoras recreacionais realizaram um teste incremental descontínuo em esteira rolante até a exaustão voluntária com coleta de sangue entre os estágios para análise do lactato. A vLL Exp (10,9 ± 0,8 km/h) foi estatisticamente diferente (P < 0,05) da vLL Pol (10,4 ± 1,1 km/h) utilizando-se o teste t de Student pareado. A correlação entre a vLL Exp e a vLL Pol foi de r = 0,84. As correlações entre a velocidade pico e as vLL foram r = 0,94 (vLLexp) e r = 0,69 (vLLpol). Foi concluído que a escolha da curva de regressão do lactato sanguíneo influi no valor da vLL, sendo a vLLpol consistentemente inferior à vLLexp.

Comparação entre os métodos direto e indireto de determinação do consumo máximo de oxigênio em mulheres corredoras

O objetivo deste estudo foi comparar os valores de <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx determinados diretamente por um sistema de ergoespirometria com os valores preditos indiretamente pelo sistema ErgoPC durante um teste de esforço máximo realizado por mulheres corredoras. Participaram 20 mulheres corredoras treinadas (42,7 ± 6,4 anos; 1,64 ± 0,04m; 58,3 ± 5,8kg; IMC 21,7 ± 1,9kg/m² e 22,3 ± 3,5%G). Os sujeitos foram submetidos à avaliação da composição corporal e a um teste de esforço progressivo em esteira ergométrica (Inbrasport, Porto Alegre, RS, Brasil) para mensuração da aptidão aeróbia (<img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx). A velocidade inicial foi de 7km/h com incrementos de 1km/h a cada três minutos, sendo mantida uma inclinação constante durante todo o teste equivalente a 1%. As participantes foram fortemente estimuladas a permanecerem no teste o maior tempo possível, até a exaustão voluntária. Para a mensuração direta do <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx, foi utilizado um sistema de ergoespirometria de circuito aberto (analisador de gases Espirômetro <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" />2000 Inbrasport, Porto Alegre, Brasil). A predição indireta do <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx foi realizada através do programa ErgoPC que utiliza a fórmula de Foster (1996) para tal predição. Para a análise estatística, foi realizado o teste t de Student (p < 0,05), para a comparação dos valores de <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx obtidos de forma direta e indireta, e o teste de correlação de Pearson, para correlacionar essas duas variáveis. A medida direta do <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx apresentou valor de 51,8 ± 6,8ml/kg/min, e o indireto, 42,8 ± 3,7ml/kg/min. Na comparação entre os dois resultados foi encontrada diferença estatisticamente significante entre as variáveis. A correlação encontrada entre os valores de <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx foi de r = 0,67. Portanto, os resultados mostram que o <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx obtido de forma indireta subestima o valor da medida direta.

Validity of maximum heart rate prediction equations for children and adolescents

BACKGROUND

There are no studies in the literature to validate equations that predict maximum heart rate (HRmax) in children and adolescents.

OBJECTIVE

To analyze the validity of the HRmax predictive equations "220 - age" and "208 - (0.7 x age)" in boys aged 10 and 16.

METHODS

A progressive maximal exertion test was carried out in 69 apparently healthy boys aged 10 to 16. The initial test velocity was 9 km/h, with 1-km/h increments every three minutes. The test was maintained until maximum voluntary exertion was achieved, considering HRmax as the highest heart rate attained during the test. The measured HRmax was compared with the values predicted by the "220 - age" and "208 - (0.7 x age)" equations, using ANOVA for repeated measures.

RESULTS

The mean values of HRmax (bpm) were: 200.2 ± 8.0 (measured), 207.4 ± 1.5 ("220 - age") and 199.2 ± 1.1 ("208 - (0.7 x age)"). The HRmax predicted by the "220 - age" equation was significantly higher (p < 0.001) than the measured HRmax and the HRmax predicted by the ("208 - (0.7 x age)") equation. The correlation between the measured HRmax and age was not statistically significant (r = 0.096; p > 0.05).

CONCLUSION

The "220 - age" equation overestimated the measured HRmax and was not valid for this population. The "208 - (0.7 x age)" equation was valid for this population, showing results that were quite similar to those of measured HRmax. Future studies with larger sample sizes can verify whether the HRmax does not depend on age for this population, a situation in which the constant 200 bpm value would be more appropriate for HRmax.

The Dmax is highly related to performance in middle-aged females

The present study examined whether the running speed at the lactate threshold estimated by the maximal deviation method (LT (Dmax)) is highly correlated and in agreement with 10-km road race performance (S (10 km)) in middle-aged female runners. Additionally, the LT (Dmax) was compared with the visual detection of the inflection point (LT (Visual)), the fixed lactate level of 4 mmol.L (-1) (LT (4)) and the peak speed (S (peak)) in relation to performance. Sixteen middle-aged, recreational female runners performed a discontinuous, incremental treadmill test. The initial speed was set at 7 km.h (-1), and this speed was increased every 3 min by 1 km.h (-1) with a 30-s rest between the stages used for earlobe capillary blood sample collection. All of the participants took part in the same local 10-km road race, and S (10 km) mean speed was calculated. The speeds (mean ± SD) were 10.5 ± 1.0 (S (10 km)), 10.5 ± 1.0 (LT (Visual)), 10.9 ± 0.9 (LT (Dmax)), 11.4 ± 1.3 (LT (4)) and 13.5 ± 1.1 km.h (-1) (S (peak)). The LT (Dmax) had the narrowest limits of agreement (0.3 ± 0.4 km.h (-1)) and was the most highly correlated with the S (10 km) ( R=0.98), followed by the S (peak) ( R=0.95), LT (4) ( R=0.85) and LT (Visual) ( R=0.81). In conclusion, the LT (Dmax) should be more widely used to estimate long-distance performance and to verify improvements in training.

Componente lento do VO2 em crianças durante exercício pesado de corrida: análise com base em diferentes modelos matemáticos

O objetivo deste estudo foi verificar e quantificar a magnitude do componente lento do consumo de oxigênio (CL) em crianças submetidas a exercícios de corrida em esteira rolante, com cargas constantes de intensidade acima do limiar de lactato (75%D), utilizando para isso dois modelos de análise: a) modelo matemático com três termos exponenciais; e b) modelo deltaVO2 6-3min. Participaram do estudo oito crianças do sexo masculino (11,92 ± 0,63 anos; 44,06 ± 13,01kg; 146,63 ± 7,25cm; e níveis de maturação sexual 1 e 2), aparentemente saudáveis, não treinadas, que realizaram em diferentes dias: 1) teste incremental na esteira rolante para a determinação do consumo de oxigênio de pico (VO2pico) e do limiar de lactato (LL); e 2) dois testes de carga constante em esteira rolante durante seis minutos na intensidade de 75%delta [75%delta = LL + 0,75 x (VO2pico - LL)]. Para determinação do CL utilizaram-se: a) modelo matemático de três termos (Exp3); e b) a diferença no VO2 entre o sexto e o terceiro minuto de exercício (deltaVO2 6-3min). O CL foi expresso em valores absolutos (ml/min) e também como a contribuição percentual do CL para o aumento do VO2 no final do exercício (%CL). O CL determinado pelo modelo Exp3 (129,69 ± 75,71ml/min e 8,4 ± 2,92%) foi significantemente maior do que o obtido pelo modelo deltaVO2 6-3min (68,69 ± 102,54ml/min e 3,6 ± 7,34%). Portanto, os valores de CL obtidos em crianças durante o exercício de corrida realizado no domínio pesado (75%delta) são dependentes do modelo de análise (Exp3 x deltaVO2 6-3min).

A rare variation in the high division of the sciatic nerve surrounding the superior gemellus muscle

The sciatic nerve normally leaves the pelvis by passing through the greater sciatic foramen below piriformis. However, it may divide into its common fibular and tibial nerve components within the pelvis and its relationship with piriformis is variable. In this paper, we describe a new anatomical variation in which the common fibular nerve passed superior, and the tibial nerve inferior, to the superior gemellus muscle. Anatomical variations such as these may contribute to piriformis syndrome, coccygodynia and muscle atrophy.

Velocidade de corrida associada ao consumo máximo de oxigênio em meninos de 10 a 15 anos

O objetivo deste estudo foi determinar a influência da idade cronológica e da maturação biológica sobre o consumo máximo de oxigênio (VO2max) e a velocidade de corrida correspondente ao VO2max em crianças e adolescentes brasileiros, do sexo masculino, com idade entre 10 e 15 anos, não praticantes de atividade física sistemática. Participaram do estudo 40 voluntários, divididos em dois grupos, segundo a idade cronológica (GC1 - n = 20; 11,4 ± 0,6 anos; 38,8 ± 8,6kg; 143,6 ± 8,2cm e GC2 - n = 20; 14,1 ± 0,6 anos; 55,9 ± 14,2kg; 163,3 ± 10,2cm) e maturação biológica (GB1 - n = 20; estágios 1, 2 e 3; e GB2 - n = 20; estágios 4 e 5). O VO2max foi mensurado em um teste progressivo e intermitente de corrida em esteira rolante, com estágios de três minutos e pausa de 20 segundos, incrementos de 1km/h a começar com 9km/h, até a exaustão voluntária. A velocidade correspondente ao VO2max (vVO2max) foi considerada como a menor velocidade em que se observou o maior valor de VO2. A máxima velocidade aeróbia (Va max) foi calculada pela fórmula proposta por di Prampero (1986). Houve diferença significante para os valores de VO2max(l/min), Va max(km/h)e vVO2max(km/h) entre os grupos GC1 e GC2 (1,84 ± 0,41 / 2,81 ± 0,61; 11,8 ± 1,2 / 12,6 ± 1,2; 12,1 ± 1,2 / 12,9 ± 1,1, respectivamente), GB1 e GB2 (1,80 ± 0,37 / 2,87 ± 0,56; 12,1 ± 1,2 / 12,9 ± 1,1; 11,8 ± 1,2 / 12,5 ± 1,1, respectivamente), mas não para os valores de VO2max em ml.kg-1.min-1 para todos os grupos (GC1 e GC2: 47,9 ± 6,8 / 50,4 ± 5,5; GB1 e GB2: 47,9 ± 6,8 / 50,3 ± 5,5, respectivamente). Com base nos resultados obtidos, pode-se concluir que o VO2max (l/min), aVa max e a vVO2max têm seus valores aumentados como um provável efeito do crescimento e desenvolvimento, podendo, ainda, expressar melhora da economia de movimento, mesmo em indivíduos não praticantes de atividade física sistemática.