Stability of the blood lactate-heart rate relationship in competitive athletes

Acute physiological outcomes of high-intensity functional training: a scoping review

Background

Systematic reviews and meta-analyses related to high-intensity functional training (HIFT) have been conducted. However, due to a restricted pool of available research, these investigations are often limited in scope. As such, a scoping review investigating the present literature surrounding the acute physiological response to HIFT-based exercise was chosen as a more appropriate structured review.

Methodology

A scoping review was conducted following Arksey and O'Malley's framework. Three large scale databases were searched to reveal any article pertaining to HIFT and related exercise terminology.

Results

A total of 2,241 articles were found during the initial search. Following this, titles, then abstracts, and full-texts were reviewed to determine inclusion eligibility. A total of 60 articles which investigated a combined total of 35 unique HIFT workouts were included within this review.

Conclusions

A variety of physiological parameters and HIFT workouts have been examined. Markers of intensity (e.g., blood lactate concentrations, heart rate) have been most consistently assessed across all studies, and these support the idea that HIFT workouts are typically performed at high-intensity. In contrast, the inclusion of most other measures (e.g., hormonal, markers of inflammation and damage, energy expenditure, performance) has been inconsistent and has thus, limited the possibility for making generalized conclusions. Differences in study methodologies have further impacted conclusions, as different studies have varied in sample population characteristics, workouts assessed, and time points. Though it may be impossible to comprehensively research all possible HIFT workouts, consistent adoption of population definitions and workload quantification may overcome this challenge and assist with future comparisons.

Quantifying CrossFit®: Potential solutions for monitoring multimodal workloads and identifying training targets

The design of high-intensity functional training (HIFT; e. g., CrossFit^®) workouts and targeted physiological trait(s) vary on any given training day, week, or cycle. Daily workouts are typically comprised of different modality and exercise combinations that are prescribed across a wide range of intensities and durations. The only consistent aspect appears to be the common instruction to maximize effort and workout density by either completing "as many repetitions as possible" within a time limit (e.g., AMRAP, Tabata) or a list of exercises as quickly as possible. However, because effort can vary within and across workouts, the impact on an athlete's physiology may also vary daily. Programming that fails to account for this variation or consider how targeted physiological systems interrelate may lead to overuse, maladaptation, or injury. Athletes may proactively monitor for negative training responses, but any observed response must be tied to a quantifiable workload before meaningful changes (to programming) are possible. Though traditional methods exist for quantifying the resistance training loads, gymnastic movements, and cardiorespiratory modalities (e.g., cycling running) that might appear in a typical HIFT workout, those methods are not uniform, and their meaning will vary based on a specific exercise's placement within a HIFT workout. To objectively quantify HIFT workloads, the calculation must overcome differences in measurement standards used for each modality, be able to account for a component's placement within the workout and be useful regardless of how a workout is commonly scored (e.g., repetitions completed vs. time-to-completion) so that comparisons between workouts are possible. This review paper discusses necessary considerations for quantifying various HIFT workout components and structures, and then details the advantages and shortcomings of different methods used in practice and the scientific literature. Methods typically used in practice range from being excessively tedious and not conducive for making comparisons within or across workouts, to being overly simplistic, based on faulty assumptions, and inaccurate. Meanwhile, only a few HIFT-related studies have attempted to report relevant workloads and have predominantly relied on converting component and workout performance into a rate (i.e., repetitions per minute or second). Repetition completion rate may be easily and accurately tracked and allows for intra- and inter-workout comparisons. Athletes, coaches, and sports scientists are encouraged to adopt this method and potentially pair it with technology (e.g., linear position transducers) to quantify HIFT workloads. Consistent adoption of such methods would enable more precise programming alterations, and it would allow fair comparisons to be made between existing and future research.

Predicting Cardiorespiratory Fitness in Female Soccer Players: The Basque Female Football Cohort Study

PURPOSE

To develop gender-specific operational equations for prediction of cardiorespiratory fitness in female footballers.

METHOD

Forty-eight semiprofessional female footballers performed an intermittent progressive maximal running test for determination of fixed blood lactate concentration (FBLC) thresholds. Relationships between FBLC thresholds and the physiological responses to submaximal running were examined. Developed equations (n = 48) were compared with equations previously obtained in another investigation performed in males (n = 100).

RESULTS

Submaximal velocity associated with 90% maximal heart rate was related to FBLC thresholds (r = .76 to .79; P < .001). Predictive power (R2 = .82 to .94) of a single blood lactate concentration (BLC) sample measured at 10 or 11.5 km·h-1 was very high. A single BLC sample taken after a 5-minute running bout at 8.5 km·h-1 was related to FBLC thresholds (r = -.71; P < .001). No difference (P = .15) in the regression lines predicting FBLC thresholds from velocity associated with 90% maximal heart rate was observed between the female and male cohorts. However, regressions estimating FBLC thresholds by a single BLC sample were different (P = .002).

CONCLUSIONS

Velocity associated with 90% maximal heart rate was robustly related to FBLC thresholds and might serve for mass field testing independently of sex. BLC equations accurately predicted FBLC thresholds. However, these equations are gender-specific. This is the first study reporting operational equations to estimate the FBLC thresholds in female footballers. The use of these equations reduces the burden associated with cardiorespiratory testing. Further cross-validation studies are warranted to validate the proposed equations and establish them for mass field testing.

A "Blood Relationship" Between the Overlooked Minimum Lactate Equivalent and Maximal Lactate Steady State in Trained Runners. Back to the Old Days?

Maximal Lactate Steady State (MLSS) and Lactate Threshold (LT) are physiologically-related and fundamental concepts within the sports and exercise sciences. Literature supporting their relationship, however, is scarce. Among the recognized LTs, we were particularly interested in the disused “Minimum Lactate Equivalent” (LE_min), first described in the early 1980s. We hypothesized that velocity at LT, conceptually comprehended as in the old days (LE_min), could predict velocity at MLSS (_VMLSS) more accurate than some other blood lactate-related thresholds (BL_RTs) routinely used nowadays by many sport science practitioners. Thirteen male endurance-trained [_VMLSS 15.0 ± 1.1 km·h⁻¹; maximal oxygen uptake (V.O2max) 67.6 ± 4.1 ml·kg⁻¹·min⁻¹] homogeneous (coefficient of variation: ≈7%) runners conducted 1) a submaximal discontinuous incremental running test to determine several BL_RTs followed by a maximal ramp incremental running test for V.O2max determination, and 2) several (4–5) constant velocity running tests to determine _VMLSS with a precision of 0.20 km·h⁻¹. Determined BL_RTs include LE_min and LE_min-related LE_min plus 1 (LE_min+1mM) and 1.5 mmol·L⁻¹ (LE_min+1.5mM), along with well-established BL_RTs such as conventionally-calculated LT, D_max and fixed blood lactate concentration thresholds. LE_min did not differ from LT (P = 0.71; ES: 0.08) and was 27% lower than MLSS (P < 0.001; ES: 3.54). LE_min+1mM was not different from MLSS (P = 0.47; ES: 0.09). LE_min was the best predictor of _VMLSS (r = 0.91; P < 0.001; SEE = 0.47 km·h⁻¹), followed by LE_min+1mM (r = 0.86; P < 0.001; SEE = 0.58 km·h⁻¹) and LE_min+1.5mM (r = 0.84; P < 0.001; SEE = 0.86 km·h⁻¹). There was no statistical difference between MLSS and estimated MLSS using LE_min prediction formula (P = 0.99; ES: 0.001). Mean bias and limits of agreement were 0.00 ± 0.45 km·h⁻¹ and ±0.89 km·h⁻¹. Additionally, LE_min, LE_min+1mM and LE_min+1.5mM were the best predictors of V.O2max (r = 0.72–0.79; P < 0.001). These results support LE_min, an objective submaximal overlooked and underused BL_RT, to be one of the best single MLSS predictors in endurance trained runners. Our study advocates factors controlling LE_min to be shared, at least partly, with those controlling MLSS.

Aerobic Cycle Exercising in a Rehabilitation Program with a Wider Choice of Intensity

When patients in rehabilitation programs use cycle ergometers for aerobic fitness training, the exercise intensity is often restricted to a small range of heart rate. In this study, a wider choice of intensities was left to the patients without giving up the potential to reduce cardiac risks factors. 24 patients in 3-wk. rehabilitation programs could choose the exercise intensity up to a workload limit preset by the physical therapist. 20 of them exercised at an intensity covering the full range between the aerobic and anaerobic lactate threshold and 4 a little above. The opportunity to vary the workload was frequently used by 67%. In 75% of the exercise sessions, the patients' average heart rates exceeded moderate heart-rate targets recommended in rehabilitation and health promotion for people with moderate cardiac risks without a graded exercise test. In 72% of these sessions, the anaerobic lactate threshold at 4 mmol/L was not exceeded. But a tendency of 33% of the patients to exercise at higher blood lactate or blood pressure levels underlined the necessity of limiting the exercise intensity.

Knee stability, athletic performance and sport-specific tasks in non-professional soccer players after ACL reconstruction: comparing trans-tibial and antero-medial portal techniques

BACKGROUND

a wrong position of bone tunnels, in particular on the femur, is one of the most frequent causes of a failed anterior cruciate ligament (ACL) reconstruction. Several studies demonstrated that drilling the femoral tunnel through the antero-medial portal (AMP) allows a more anatomical placement on the lateral femoral condyle and higher knee stability, compared to trans-tibial (TT) technique. The aim of this study was to retrospectively evaluate two groups of soccer players operated on for ACL reconstruction according to either one of these two techniques.

METHODS

two groups of non-professional soccer players operated on for a single bundle ACL reconstruction with hamstrings autograft using either a TT (20 patients) or an AMP (23 patients) technique were retrospectively evaluated with KT-1000 arthrometer, manual pivot shift test, isokinetic test, the incremental treadmill-running test, athletic and sport specific tasks, and knee scores (IKDC, Lysholm and KOOS).

RESULTS

the AMP group showed better results at pivot shift test and KOOS, but lower flexion angles at single leg squat test. There were no differences in all the other considered outcomes.

CONCLUSIONS

the better rotational stability of the knee achieved in AMP group did not lead to significantly better clinical and functional results in our patients.

LEVEL OF EVIDENCE III TREATMENT STUDY

Case-control study.

Performance characteristics of long-track speed skaters: a literature review

Speed skating is an intriguing sport to study from different perspectives due to the peculiar way of motion and the multiple determinants for performance. This review aimed to identify what is known on (long-track) speed skating, and which individual characteristics determine speed skating performance. A total of 49 studies were included. Based on a multidimensional performance model, person-related performance characteristics were categorized in anthropometrical, technical, physiological, tactical, and psychological characteristics. Literature was found on anthropometry, technique, physiology, and tactics. However, psychological studies were clearly under-represented. In particular, the role of self-regulation might deserve more attention to further understand mechanisms relevant for optimal performance and for instance pacing. Another remarkable finding was that the technically/biomechanically favourable crouched skating technique (i.e. small knee and trunk angle) leads to a physiological disadvantage: a smaller knee angle may increase the deoxygenation of the working muscles. This is an important underlying aspect for the pacing tactics in speed skating. Elite speed skaters need to find the optimal balance between obtaining a fast start and preventing negative technical adaptations later on in the race by distributing their available energy over the race in an optimal way. More research is required to gain more insight into how this impacts on the processes of fatigue and coordination during speed skating races. This can lead to a better understanding on how elite speed skaters can maintain the optimal technical characteristics throughout the entire race, and how they can adapt their pacing to optimize all identified aspects that determine performance.

Heart Rate-Based Prediction of Fixed Blood Lactate Thresholds in Professional Team-Sport Players

The aim of this study was to investigate whether the speed associated with 90% of maximal heart rate (S90%HRmax) could predict speeds at fixed blood lactate concentrations of 3 mmol·L(-1) (S3mM) and 4 mmol·L(-1) (S4mM). Professional team-sport players of futsal (n = 10), handball (n = 16), and basketball (n = 10) performed a 4-stage discontinuous progressive running test followed, if exhaustion was not previously achieved, by an additional maximal continuous incremental running test to attain maximal heart rate (HRmax). The individual S3mM, S4mM, and S90%HRmax were determined by linear interpolation. S3mM (11.6 ± 1.5 km·h(-1)) and S4mM (12.5 ± 1.4 km·h(-1)) did not differ (p > 0.05) from S90%HRmax (12.0 ± 1.2 km·h(-1)). Very large significant (p < 0.001) relationships were found between S90%HRmax and S3mM (r = 0.82; standard error of the estimates [SEE] = 0.87 km·h(-1)), as well as between S90%HRmax and S4mM (r = 0.82; SEE = 0.87 km·h(-1)). S3mM and S4mM inversely correlated with %HRmax associated with running speeds of 10 and 12 km·h(-1) (r = 0.78-0.81; p < 0.001; SEE = 0.94-0.87 km·h(-1)). In conclusion, S3mM and S4mM can be accurately predicted by S90%HRmax in professional team-sport players.

Clinical Outcomes and Return-to-Sports Participation of 50 Soccer Players After Anterior Cruciate Ligament Reconstruction Through a Sport-Specific Rehabilitation Protocol

Background:

Rehabilitation of soccer players after anterior cruciate ligament reconstruction is usually performed without sport-specific guidelines, and the final phases are often left to the team coaches. The possibility of changing this approach has not yet been investigated.

Study Design:

Case series.

Hypothesis:

A specific rehabilitation protocol for soccer players, with direct control of the last on-field rehabilitation phases, may lead to complete functional recovery.

Methods:

Fifty competitive soccer players who followed a sport-specific rehabilitation protocol for soccer were evaluated during the recovery period until their return to competition. The assessment of the functional outcomes was performed using the Knee Outcome Survey–Sports Activity Scale and isokinetic and aerobic fitness tests.

Results:

The average start of on-field rehabilitation was 90 ± 26 days after surgery; the average time to return to the competitions was 185 ± 52 days. The improvement in the Knee Outcome Survey–Sports Activity Scale during on-field rehabilitation was significant (P < 0.01; from 79 ± 15% to 96 ± 7%). The isokinetic and aerobic fitness tests showed a significant improvement of muscle strength (knee extensors, +55%, P < 0.01; knee flexors, +86%, P < 0.01) and aerobic threshold (+23%, P < 0.01) from the beginning to the end of on-field rehabilitation.

Conclusions:

Adding on-field rehabilitation to the traditional protocols after anterior cruciate ligament reconstruction may safely lead to complete functional recovery in soccer players.

Resposta da frequência cardíaca e da concentração de lactato após cada segmento do triathlon olímpico

INTRODUÇÃO: As respostas fisiológicas de cada uma das modalidades envolvidas no triathlon são diferentes. Cargas de treino poderiam ser melhores prescritas se consideradas as individualidades fisiológicas de cada segmento para cada atleta. OBJETIVO: Observar o comportamento das variáveis fisiológicas, frequência cardíaca (FC) e concentração de lactato sanguíneo, antes e depois de cada segmento do triathlon: natação, ciclismo e corrida. MÉTODOS: Doze atletas do sexo masculino cumpriram uma prova de triathlon com distância olímpica. Coletas de sangue da polpa digital foram feitas antes do início da prova, após a natação, após o ciclismo, após a corrida e, ainda, uma hora após a prova. Cada atleta foi monitorizado com frequencímetro (Polar® S610) durante toda a prova. Análises estatísticas foram realizadas através da correlação de Spearman e teste de Wilcoxon para amostras não paramétricas (p<0,05). RESULTADOS: Nesta pesquisa, a maior intensidade foi registrada, em ambos os parâmetros fisiológicos, durante o ciclismo (86,3% da frequencia cardíaca máxima (FCmáx); 6,98mmol), seguida pela natação (85,2% FCmáx; 5,75mmol) e corrida (83,6% FCmáx; 4,47mmol), respectivamente. CONCLUSÃO: Conclui-se que a prescrição da carga de treino para o triathlon será mais eficiente se baseada nas respostas fisiológicas (FC e o lactato sanguíneo) individuais de cada modalidade.

Current concepts for rehabilitation and return to sport after knee articular cartilage repair in the athlete

Articular cartilage injury is observed with increasing frequency in both elite and amateur athletes and results from the significant acute and chronic joint stress associated with impact sports. Left untreated, articular cartilage defects can lead to chronic joint degeneration and athletic and functional disability. Treatment of articular cartilage defects in the athletic population presents a therapeutic challenge due to the high mechanical demands of athletic activity. Several articular cartilage repair techniques have been shown to successfully restore articular cartilage surfaces and allow athletes to return to high-impact sports. Postoperative rehabilitation is a critical component of the treatment process for athletic articular cartilage injury and should take into consideration the biology of the cartilage repair technique, cartilage defect characteristics, and each athlete's sport-specific demands to optimize functional outcome. Systematic, stepwise rehabilitation with criteria-based progression is recommended for an individualized rehabilitation of each athlete not only to achieve initial return to sport at the preinjury level but also to continue sports participation and reduce risk for reinjury or joint degeneration under the high mechanical demands of athletic activity.

Quantifying training intensity distribution in a group of Norwegian professional soccer players

PURPOSE

This study was designed to quantify the daily distribution of training intensity in a group of professional soccer players in Norway based on three different methods of training intensity quantification.

METHODS

Fifteen male athletes (age, 24 ± 5 y) performed treadmill test to exhaustion to determine heart rate and VO2 corresponding to ventilatory thresholds (VT1, VT2), maximal oxygen consumption (VO2max) and maximal heart rate. VT1 and VT2 were used to delineate three intensity zones based on heart rate. During a 4 wk period in the preseason (N = 15), and two separate weeks late in the season (N = 11), all endurance and on-ball training sessions (preseason: N = 378, season: N= 78) were quantified using continuous heart rate registration and session rating of perceived exertion (sRPE). Three different methods were used to quantify the intensity distribution: time in zone, session goal and sRPE.

RESULTS

Intensity distributions across all sessions were similar when based on session goal or by sRPE. However, intensity distribution based on heart rate cut-offs from standardized testing was significantly different (time in zone).

CONCLUSIONS

Our findings suggest that quantifying training intensity by using heart rate based total time in zone is not valid for describing the effective training intensity in soccer. The results also suggest that the daily training intensity distribution in this representative group of high level Norwegian soccer players is organized after a pattern where about the same numbers of training sessions are performed in low lactate, lactate threshold, and high intensity training zones.

Training methods and intensity distribution of young world-class rowers

PURPOSE

To describe the distribution of exercise types and rowing intensity in successful junior rowers and its relation to later senior success.

METHODS

36 young German male rowers (31 international, 5 national junior finalists; 19.2 +/- 1.4 y; 10.9 +/- 1.6 training sessions per week) reported the volumes of defined exercise and intensity categories in a diary over 37 wk. Training categories were analyzed as aggregates over the whole season and also broken down into defined training periods. Training organization was compared between juniors who attained national and international senior success 3 y later.

RESULTS

Total training time consisted of 52% rowing, 23% resistance exercise, 17% alternative training, and 8% warm-up programs. Based on heart rate control, 95% of total rowing was performed at intensities corresponding to <2 mmol x L(-1), 2% at 2 to 4 mmol x L(-1), and 3% at >4 mmol x L(-1) blood lactate. Low-intensity work remained widely unchanged at approximately 95% throughout the season. In the competition period, the athletes exhibited a shift within <2 mmol exercise toward lower intensity and within the remaining approximately 5% of total rowing toward more training near maximal oxygen consumption (VO(2max)) intensity. Retrospectively, among subjects going on to international success 3 y later had their training differed significantly from their peers only in slightly higher volumes at both margins of the intensity scope.

CONCLUSION

The young world-class rowers monitored here exhibit a constant emphasis on low-intensity steady-state rowing exercise, and a progressive polarization in the competition period. Possible mechanisms underlying a potential association between intensity polarization and later success require further investigation.

Use of an Audio-Paced Incremental Swimming Test in Young National-Level Swimmers

Purpose:

To evaluate the reliability and sensitivity to training of an audio-paced incremental swimming test.

Methods:

Eight young national-level male swimmers (age 15 ± 1 year) performed a 7 × 200-m incremental swimming test (velocities 1.19, 1.24, 1.28, 1.33, 1.39, and 1.45 m/s and maximal sprint pace) using an audio-pacing device. The same test was performed 4 times by each participant, 1 wk apart to assess reliability (WK1, WK2) and after 9 and 20 wk of training (WK9, WK20). Blood lactate concentration ([La−]) and heart rate (HR) were recorded after each stage. Outcome measures were the velocity (v) and HR at lactate markers of 2 mM, 4 mM, and Δ1 mM.

Results:

Velocities at the lactate markers proved to be more reliable than HR, with typical errors ranging from 0.66% to 2.30% and 1.28% to 4.50%, respectively (shifts in mean ranged –0.91% to 0.73% and –0.84% to 1.79%, respectively). Across WK1, WK9, and WK20 there were significant improvements in peak velocity (P < .001) and each of the velocities associated with the lactate markers (P < .05), whereas only HR at Δ1 mM improved (P < .05).

Conclusions:

This article demonstrates that an audio-paced incremental swimming test is reliable for use with junior swimmers and is sensitive to changes observed after training. The postswimming measurement of HR in the pool was comparatively less reliable.

Effect of stage duration on physiological variables commonly used to determine maximum aerobic performance during cycle ergometry

In this study, we examined the effect of stage duration on physiological variables commonly used to determine maximum aerobic performance during cycle ergometry. Ten recreationally trained males (mean age 27.8 +/- 7.1 years; BMI 24.3 +/- 2.5 kg x m(-2); VO2max 52.5 +/- 5.9 ml x kg(-1) x min(-1)) performed three different stage duration protocols on two separate occasions. Each short stage (SS; 1-min stages), long stage (LS; 3-min stages), and constant load + short stage (CL + SS; 4-min constant load followed by 1-min stages) protocol started at 50 W with increments of 30 W. The physiological variables measured included: time to maximum, maximum workload, maximum oxygen consumption (VO2max), maximum heart rate, maximum rating of perceived exertion, maximum blood lactate concentration, and maximum respiratory exchange ratio. The ventilatory threshold was calculated for every trial of the three protocols. There was no difference in VO2max, but maximum heart rate was higher in the LS protocol (P<0.05). Maximum respiratory exchange ratio varied between the protocols (P<0.05), while maximum workload differed between the SS and LS protocols, and the LS and CL + SS protocols (P<0.0001). The physiological variables were comparable between trials for the SS and CL + SS protocols, but maximum workload and VO2max differed for the LS protocol (P<0.05). Workload at the ventilatory threshold was lower for the LS protocol (P<0.05). Heart rate at the ventilatory threshold was different between the LS and CL + SS protocols (P<0.05). Performing a test involving 1- or 3-min stage durations on a single occasion was appropriate for the determination of VO2max and the ventilatory threshold. However, the disparity in heart rate and workload could result in differences in mechanical and physiological work being undertaken. Consistent use of a protocol may alleviate errors during exercise prescription.

A Pilot Study to Assess the Feasibility of a Submaximal Exercise Test to Measure Individual Response to Cardiac Medication in Dogs with Acquired Heart Failure

Exercise testing is not commonly used in canine medicine because of several limitations. The aim of this study was to investigate the suitability of a treadmill test to measure the exercise capacity of untrained canine cardiac patients and to measure some biological parameters that might reflect the tolerance of dogs with heart failure to submaximal exercise. The exercise capacity of seven dogs with naturally occurring heart failure was evaluated before the institution of cardiac medication and 7 days after the beginning of the study. An additional re-examination was requested after 28 days. The exercise test was performed on a motorized treadmill at three different speeds (0.5 m/s, 1.0 m/s and 1.5 m/s). The following parameters were measured at the end of each stage and after 20 min recovery: heart rate, rectal temperature, glucose, lactate, aspartate aminotransferase, creatine kinase, PvO(2), PvCO(2), pH, haematocrit, bicarbonate, sodium, potassium and chloride. Serum cardiac troponin-I was also measured at the beginning of the test and at the end of the recovery period. Owners' perception reflected the ability of their dogs to exercise on the treadmill. Lactate level increased noticeably with the intensity of the exercise test, and its variation coincided with different exercise tolerance observed by the owners. Heart rate seemed to follow a similar trend in the few dogs presented in sinus rhythm. None of the remaining parameters appeared to be sensitive indicators of activity level in the dogs used in this study. The treadmill exercise test in dogs with acquired heart failure is feasible and might provide useful information for assessing individual response to cardiac medication. Lactate and heart rate seemed to reflect individual levels of exercise tolerance, although further studies are necessary to confirm the reliability and repeatability of this test.

Determination and validity of critical swimming velocity in elite physically disabled swimmers

The purpose of this investigation was to determine if the critical swimming velocity (CSV), defined as the theoretical maximal swimming velocity that could be maintained for a long period of time without exhaustion, corresponds to the exercise intensity at onset blood lactate accumulation (OBLA), and if it could be utilized as a practical index for assessing endurance performance in elite physically disabled swimmers. Eight elite physically disabled swimmers swam four different distances (50, 100, 200 and 400 m) at maximal effort. The swimming time was taken during each trial. The CSV was expressed as the slope of a regression line between the covered swimming distance and the corresponding times of all possible combinations of 2 or 4 time trials. Results indicate that all the CSVs calculated were similar independently of the distances utilized for their calculation. Afterwards, a CSV confirmation test consisting of 3 x 10-min trials at 95, 100, 105% of the CSV was carried out. The lactate concentration at the end of each trial was 3.32, 4.03 and 5.73 mmol x l(-1), respectively. Lactate concentration at 100% CSV approached the value of 4 mmol x l(-1), which is considered the exercise intensity at OBLA. We conclude that the CSV corresponds with the OBLA intensity and could be a valuable index to plan a training schedule for physically disabled swimmers.

A Simplified Strategy for the Estimation of the Exercise Ventilatory Thresholds

PURPOSE

To analyze the limits of agreement between exercise ventilatory threshold values (VT1 and VT2) estimated from a combination of pulmonary gas exchange and ventilatory variables (cardiopulmonary exercise testing) and those derived from an alternative approach based on the ventilatory response only (V(E), ventilometry).

METHODS

Forty-two nontrained subjects (24 males, aged 18-48, peak VO(2) = 33.1 +/- 8.6 mL.min(-1).kg(-1)) performed a maximum incremental cardiopulmonary exercise testing on an electromagnetically braked cycle ergometer. The participants breathed through a Pitot tube (Cardio2 System, MGC) and a fixed-resistance ventilometer (Micromed, Brazil), which were connected in series. HR values at the estimated VT (VTHR1 and VTHR2) were obtained by the conventional method (ventilatory equivalents, end-expiratory pressures for O(2) and CO(2), and the V-slope procedure) and an experimental approach (V(E) vs time, V(E)/time vs time, and breathing frequency vs time).

RESULTS

There were no significant between-method differences on VT(HR1), VT(HR2), VT(VE1), VT(VE2), and peak V(E) (P > 0.05). After certification of data normality, a Bland-Altman analysis revealed that the mean bias +/- 95% confidence interval of the between-method differences were lower for VT(HR2) than VT(HR1) (2 +/- 9 and 0 +/- 17 bpm, respectively). VT(HR2) according to ventilometry differed more than 10 bpm from the standard procedure in 3 out of 42 subjects (9%). Between-method differences were independent of the level of fitness, as estimated from peak VO(2) (P > 0.05).

CONCLUSIONS

: A simplified approach, based on the ventilatory response as a function of time, can provide acceptable estimates of the exercise ventilatory thresholds--especially VT2--during ramp-incremental cycle ergometry. This new strategy might prove to be useful for exercise training prescription in nontrained adults.

Seasonal changes in power of competitive cyclists: Implications for monitoring performance

Sport scientists should consider seasonal trends and individual variability in performance when using tests to track performance changes resulting from training or other medium-term interventions with individuals or in research studies. We report here the seasonal changes and variability in power of 12 male competitive cyclists, who performed laboratory tests of incremental peak and 4-km mean power measured with three ergometers simultaneously in each of five sessions during three phases (base, pre-comp, comp) of a season. Repeated-measures analysis of log-transformed power provided mean percent changes in performance between phases and within-cyclist variability in performance expressed as coefficients of variation between sessions < or = 2 wk apart within a phase and between sessions 8 wk-12 wk apart in different phases. Peak power increased from the base phase to the pre-comp phase on average by 5.3%, and by a further 1.8% from pre-comp to comp phase; corresponding increases in 4-km mean power were 6.1% and 2.2% (90% likely limits all approximately +/-2.6%). The variabilities for peak and 4-km mean powers were 1.2%-1.8% for sessions separated by < or = 2 wk and 2.0%-2.3% for sessions in pre-comp and comp phases, but increased to 3.4%-3.8% for sessions between the base and other phases (likely limits approximately (x/)/(1.6). Individual differences in the improvement in performance after the base phase evidently produced the greater variability between the base and the other phases. Interventions that might produce small but worthwhile changes in performance over a period of weeks-months need to be researched in pre-comp and comp phases, when the variability is small.

Assessment of ventilatory thresholds during graded and maximal exercise test using time varying analysis of respiratory sinus arrhythmia

OBJECTIVE

To test whether ventilatory thresholds, measured during an exercise test, could be assessed using time varying analysis of respiratory sinus arrhythmia frequency (f(RSA)).

METHODS

Fourteen sedentary subjects and 12 endurance athletes performed a graded and maximal exercise test on a cycle ergometer: initial load 75 W (sedentary subjects) and 150 W (athletes), increments 37.5 W/2 min. f(RSA) was extracted from heart period series using an evolutive model. First (T(V1)) and second (T(V2)) ventilatory thresholds were determined from the time course curves of ventilation and ventilatory equivalents for O(2) and CO(2).

RESULTS

f(RSA) was accurately extracted from all recordings and positively correlated to respiratory frequency (r = 0.96 (0.03), p<0.01). In 21 of the 26 subjects, two successive non-linear increases were determined in f(RSA), defining the first (T(RSA1)) and second (T(RSA2)) f(RSA) thresholds. When expressed as a function of power, T(RSA1) and T(RSA2) were not significantly different from and closely linked to T(V1) (r = 0.99, p<0.001) and T(V2) (r = 0.99, p<0.001), respectively. In the five remaining subjects, only one non-linear increase was observed close to T(V2). Significant differences (p<0.04) were found between athlete and sedentary groups when T(RSA1) and T(RSA2) were expressed in terms of absolute and relative power and percentage of maximal aerobic power. In the sedentary group, T(RSA1) and T(RSA2) were 150.3 (18.7) W and 198.3 (28.8) W, respectively, whereas in the athlete group T(RSA1) and T(RSA2) were 247.3 (32.8) W and 316.0 (28.8) W, respectively.

CONCLUSIONS

Dynamic analysis of f(RSA) provides a useful tool for identifying ventilatory thresholds during graded and maximal exercise test in sedentary subjects and athletes.

Does intermittent hypoxia increase erythropoiesis in professional cyclists during a 3-week race?

In this study we examined the effects of intermittent hypoxia exposure (IHE) in a group of professional cyclists (n = 6; age 26 +/- 1 yr) competing in the 2001 Vuelta a España. After each daily stage, treated subjects received four 5-min bouts of normobaric IHE (mean O2 concentration of 12.6%, simulating a mean altitude of 4,000 m) interspersed with 5-min bouts of breathing hotel room air (normoxia) until completing a total IHE of 20-min duration. The primary outcome, compared to a control group of similar characteristics not receiving IHE (n = 5; age 25 +/- 1 yr), was the % increase in erythropoietin (Epo) from the beginning to the end of the Vuelta. Statistical analysis showed that Epo increase tended to be higher (p = 0.052) in the IHE group than in controls (37.4 +/- 5.8% vs. -4.4 +/- 19.5%, respectively). However IHE had no effect on reticulocytes or erythrocyte count (p > 0.05).

Return to official Italian First Division soccer games within 90 days after anterior cruciate ligament reconstruction: a case report

STUDY DESIGN

Case report.

BACKGROUND

To present the rehabilitative course, decision-making, and clinical milestones that allowed a top-level professional soccer player to return to full competitive activity 90 days after surgery.

CASE DESCRIPTION

The patient was a 35-year-old forward player who sustained an isolated complete tear of the left anterior cruciate ligament (ACL) in the midst of the competitive 2001-2002 season. He was in contention for a position on the Italian World Cup Team that was to be played 135 days after his injury, only if he demonstrated that he could return to play at the highest level before the team was selected. The patient underwent an arthroscopically assisted ACL reconstruction with a double-loop semitendinosus-gracilis autograft 4 days after the injury. Eight days after surgery he began rehabilitation at a rate of 2 sessions a day, 5 days a week, plus 1 session every Saturday morning. These sessions were performed in a pool for aquatic exercises, in a gymnasium for flexibility, coordination, and strength exercises, and on a soccer field for recovery of technical and tactical skills, with continuous monitoring of training intensity.

OUTCOMES

The surgical technique and the progressive rehabilitation program allowed the patient to play for 20 minutes in an official First Division soccer game 77 days after surgery and to play a full game 90 days after surgery. Eighteen months postsurgery, the player had participated in 62 First Division matches, scoring 26 times, and had received no further treatment for his knee.

DISCUSSION

This case report suggests that early return to high-level competition after ACL reconstruction is possible in some instances. Some factors that may have favored the early return include optimal physical fitness before surgery, a strong psychological determination, an isolated ACL lesion, a properly placed and tensioned graft, a personalized progression of volume and intensity of exercise loads, and an appropriate density of rehabilitative training consisting of a mix of gymnasium, pool, and field exercises.

Exercise with the Intensity of the Individual Anaerobic Threshold in Acute Hypoxia

PURPOSE

The aim of the present study was to find out if the determination of the individual anaerobic threshold (IAT) during incremental treadmill tests in normoxia and acute normobaric hypoxia (FiO2 0.15) defines equivalent relative submaximal intensities in these environmental conditions.

METHODS

11 male middle and long distance runners performed a 1-h treadmill run in normoxia and hypoxia at the intensity of the IAT determined in the respective environment with measurement of lactate, glucose, heart rate, catecholamines, ventilatory parameters, and rate of perceived exertion (RPE).

RESULTS

During the 1-h treadmill runs, speed was significantly reduced in hypoxia compared with normoxia (12.8 +/- 0.7 vs 14.7 +/- 0.7 km x h(-1)). Relative intensity expressed as a percentage of VO(2max) was similar in both environments (82-83% on the average) and elicited comparable lactate steady states [LaSS, 2.5 +/- 0.7 - 3.4 +/- 1.1 mmol x L(-1) (normoxia), 2.7 +/- 0.8 - 3.6 +/- 1.0 mmol x L(-1) (hypoxia) after 10 and 60 min, respectively] and glucose levels, but significantly reduced heart rate in hypoxia by 5 beats x min(-1) on the average. A steady state was also found for the ventilatory parameters. Plasma epinephrine and norepinephrine levels were similar in both environments. RPE was significantly lower after 40-60 min of exercise in hypoxia.

CONCLUSIONS

Relative intensities in normoxia and acute hypoxia are equivalent when endurance exercise is performed with the running speed at the IAT determined in the respective environment. The heart rate-blood lactate relationship, however, is changed in hypoxia and relative submaximal exercise intensity is higher in acute hypoxia when training is performed with similar heart rate as in normoxia.

Stability of dyspnea ratings after exercise training in patients with COPD

PURPOSE

The purpose of this study was to examine whether patients with chronic obstructive pulmonary disease (COPD) would report similar ratings of dyspnea at the same relative exercise intensity after participation in pulmonary rehabilitation.

METHODS

Forty-two patients with COPD performed incremental cardiopulmonary exercise testing before and after completion of a 6-wk exercise-training program. Subjects rated dyspnea on the 0-10 category-ratio (CR-10) scale each minute of the exercise test.

RESULTS

Both responders (21 patients who exhibited an increase in [OV0312]O(2peak) after pulmonary rehabilitation) and nonresponders (21 patients who had no increase in [OV0312]O(2peak)) reported slightly lower ratings of dyspnea ( approximately 0.5 on the CR-10 scale) at the same relative (50% and 75% of [OV0312]O(2peak)) exercise intensities. These changes in dyspnea ratings after pulmonary rehabilitation were not significantly different between responders and nonresponders.

CONCLUSION

The study suggests that patients with COPD can use the same ratings of dyspnea to monitor training at the same relative exercise intensity whether they achieve a physiological training response or not.

Tour de France versus Vuelta a España: which is harder?

PURPOSE

To compare the total exercise loads (intensity x volume) of the Vuelta a España and Tour de France during the last year.

METHODS

Seven professional road cyclists (28 +/- 1 yr; [OV0312]O(2max): 74.6 +/- 2.2 mL.kg-1.min-1) who participated in both Tour and Vuelta during the years 1997, 1999, 2000, or 2001 were collected as subjects. They wore a heart rate (HR) telemeter during each stage of the two races, and exercise intensity was divided into three phases according to the reference HR values obtained during a previous ramp cycle-ergometer test: phase I (<ventilatory threshold (VT)), phase II (between VT and the respiratory compensation point (RCP)) and phase III (>RCP). Total volume and intensity were integrated as a single variable. The score for volume x intensity in each phase was computed by multiplying the accumulated duration in this phase by a multiplier for this particular phase. The total score for Tour and Vuelta was obtained by summating the results of the three phases.

RESULTS

The total loads (volume x intensity) did not significantly differ between the two races (P > 0.05), despite a significantly longer total exercise time of the Tour (P < 0.05) (5552 +/- 176 vs 5086 +/- 290 min).

CONCLUSION

The physiological loads imposed on cyclists' bodies do not differ between the Tour and Vuelta, despite the longer duration of daily stages in the former race.

Ventilatory thresholds in arm and leg exercises with spontaneously chosen crank and pedal rates

The present study assessed whether the first and the second ventilatory thresholds (VT1 and VT2) were dependent on the muscle groups solicited when spontaneously chosen crank and pedal rates are used. 20 physical education male students (22 +/- 2.2 yr.) performed two maximal incremental tests randomly assigned using an increment of 15 and 30 W every minute for arm and leg exercises, respectively. These tests were used to measure the maximal oxygen uptake (VO2 max) and to identify VT1 and VT2. The absolute oxygen uptake (VO2) values measured at VT1, VT2, and at maximal workload were significantly (p < .05) lower during arm and leg exercises. However, VT1 and VT2 expressed in percent of VO2 max were not significantly different between arm and leg exercises (54.1 +/- 8.2 vs 57.2 +/- 11.4%; and 82.5 +/- 6.4 vs 84.6 +/- 5.1% at VT1 and VT2, respectively). In addition, at the two thresholds, none of the variables measured during arm and leg exercises were significantly correlated with the exception of spontaneously chosen crank and pedal rates (p < .01; r = .75 and r = .69 for VT1 and VT2, respectively). Probably due to the different training status and skill level, no extrapolation can be made to specify the arm thresholds from the leg. These results underline the need to specify the ventilatory thresholds from specific arm ergometer measures obtained from tests performed with spontaneously chosen crank and pedal rates and, thus, close to sport and recreational activities, when they are used for training and rehabilitation programs.

Heart rate and performance parameters in elite cyclists: a longitudinal study

PURPOSE

This study was designed to evaluate the stability of target heart rate (HR) values corresponding to performance markers such as lactate threshold (LT) and the first and second ventilatory thresholds (VT1, VT2) in a group of 13 professional road cyclists (VO2max, approximately 75.0 mL x kg(-1) x min(-1)) during the course of a complete sports season.

METHODS

Each subject performed a progressive exercise test on a bicycle ergometer (ramp protocol with workload increases of 25 W x min(-1)) three times during the season corresponding to the "active" rest (fall: November), precompetition (winter: January), and competition periods (spring: May) to determine HR values at LT, VT1 and VT2.

RESULTS

Despite a significant improvement in performance throughout the training season (i.e., increases in the power output eliciting LT, VT1, or VT2), target HR values were overall stable (HR at LT: 154 +/- 3, 152 +/- 3, and 154 +/- 2 beats x min(-1); HR at VT1: 155 +/- 3, 156 +/- 3, and 159 +/- 3 beats x min(-1); and at VT2: 178 +/- 2, 173 +/- 3, and 176 +/- 2 beats x min(-1) during rest, precompetition, and competition periods, respectively).

CONCLUSION

A single laboratory testing session at the beginning of the season might be sufficient to adequately prescribe training loads based on HR data in elite endurance athletes such as professional cyclists. This would simplify the testing schedule generally used for this type of athlete.

Respostas do lactato sanguíneo e da freqüência cardíaca em duas diferentes provas do automobilismo

Com o propósito de caracterizar e avaliar as condições fisiológicas do atleta durante provas do automobilismo, um piloto profissional de alta performance foi submetido a testes de pista no Autódromo Internacional de Interlagos. Foram determinados os valores das concentrações sanguíneas de lactato e glicose de um mesmo piloto, antes e após duas provas do automobilismo: uma da Fórmula Corsa e outra do Kart, realizadas em dias diferentes. A freqüência cardíaca (FC) foi registrada a cada quinze e cinco segundos durante as competições, respectivamente. As provas foram filmadas, visando a sincronização entre os acontecimentos e a resposta da FC. Visando a avaliação do condicionamento aeróbio do atleta, seu limiar anaeróbio foi determinado em um teste padronizado de campo. Os resultados referentes às concentrações de lactato ao final das provas sugerem intensidades diferentes entre as duas, sendo a F-Kart superior em relação à F-Corsa. Houve acoplamento entre a FC e o lactato sanguíneo e isso sugere que a FC, ao menos nesse piloto experiente, não está alterada pelo risco da modalidade. A resposta da FC deve estar relacionada ao esforço físico e ansiedade de vitória semelhante a qualquer outro esporte.