Ramon Baron

A physiological profile of tennis match play

PURPOSE The aim of this investigation was to examine physiological demands of single match play in tennis. METHODS 20 players performed 10 matches of 50 min. Respiratory gas exchange measures (RGEM) and heart rates (HR) were measured using two portable systems. Lactate concentration was determined after each game. The average oxygen uptake (VO2) of 270 games was 29.1 +/- 5.6 mL.kg-1.min-1 (51.1 +/- 10.9% of VO2max). Average VO2 for a game ranged from 10.4 to 47.8 mL.kg-1.min-1 (20.4 and 86.8% of VO2max). Average lactate concentration (LA) was 2.07 +/- 0.9 mmol.L-1 (ranging from 0.7 to 5.2 mmol.L-1). Furthermore, we monitored the duration of rallies (DR), the effective playing time (EPT), and the stroke frequency (SF). The average values of 270 games were DR: 6.4 +/- 4.1 s, EPT: 29.3 +/- 12.1%, SF: 42.6 +/- 9.6 shots.min-1. RESULTS Multiple regression revealed that the DR was the most promising variable for the determination of VO2 in match play (r = 0.54). The body surface area (BSA) and EPT were also entered into the calculation model. In games of two defensive players, VO2 was significantly higher than in games with at least one offensive player. CONCLUSION Our results suggest that energy demands of tennis matches are significantly influenced by DR. The highest average VO2 of a game of 47.8 mL.kg-1.min-1 may be regarded as a guide to assess endurance capacity required to sustain high-intensity periods of tennis matches compared with average VO2 of 29.1 mL.kg-1.min-1 for the 270 games. Our results suggest that proper conditioning is advisable especially for players who prefer to play from the baseline.

Sprinting analysis of elite soccer players during European Champions League and UEFA Cup matches

Abstract It has been suggested that assessment of high-intensity activities during a match is a valid measure of physical performance in elite soccer. Recently, sprinting activities have been analysed in more depth. The aim of this study was to develop a detailed analysis of the sprinting activities of different playing positions during European Champions League and UEFA Cup competitions. Altogether, 717 elite outfield soccer players were evaluated throughout 2002–2006 using ProZone® (Leeds, UK). Sprinting (explosive and leading) was analysed for each playing position. To compare positional differences, a Kruskal-Wallis analysis was performed. Differences were found among positions for total number of sprints and total sprint distance covered: wide midfielders > (attackers = wide defenders) > central midfielders > central defenders (P < 0.001), as well as for explosive sprints: (wide midfielders = attackers = wide defenders) > central defenders, wide midfielders > central midfielders > central defenders and attackers = wide defenders = central midfielders (P < 0.001), and leading sprints: wide midfielders > (attackers = wide defenders) > central midfielders > central defenders (P < 0.001). For each group, there were no differences in ratio of explosive to leading sprints. Wide midfielders performed a higher number of sprints in all five distance categories than all other positions. This study showed that sprinting characteristics are influenced by position. Wide midfielders have to complete additional high-intensity activities during training sessions compared with the other positions to achieve the performance level required during the match.

Aerobic and anaerobic power characteristics of off-road cyclists

PURPOSE The purpose of this study was to describe the relationship between anaerobic power at different pedaling frequencies (including the optimal cadence) and aerobic power in off-road cyclists (CYC; N = 25) and sports students, who did not perform specific cycle exercise more than two times per week (CON; N = 60). METHODS To describe the aerobic power, we measured the maximal power output (W(max)) and the power output at the fixed lactate threshold at 4 mmol x L(-1) (W(L4)) obtained during a maximal aerobic power cycling test. To describe anaerobic power output, we measured the average power output (IsoW(mean)) over a range from 50 to 140 rpm by using a 10-s sprint on an isokinetic cycle ergometer. RESULTS For the 10-s anaerobic test, CON and CYC showed a peak power output (IsoW(peak)) of 13.3 +/- 1.4 and 14.9 +/- 1.1 W x kg(-1), respectively. IsoW(peak) corresponded to an optimal cadence of 100 +/- 9.3 rpm for CON and 100 +/- 8.7 rpm for CYC. There was a significant difference (P < 0.001) in the W(max):IsoW(peak) (W(aerobic):W(anaerobic)) ratio between CON (32 +/- 4.5%) and CYC (38 +/- 3.9%). Significant differences among group means were identified using an ANOVA test and a post hoc analysis. The off-road cyclists showed a significantly higher IsoW(mean) at all pedaling frequencies and at the optimal cadence (P < 0.01). There was a modest relationship between W(max) and IsoW(peak) in both groups (CON r = 0.53; CYC r = 0.64; P < 0.01). CONCLUSION Anaerobic power values are important components associated with cycle performance in both noncyclists and off-road cyclists. However, the results of the present study demonstrated the usefulness of the power index in the physiological evaluation of off-road cyclists, as it gives information on the proportion of aerobic to anaerobic energy contribution.

Muscle function after endoprosthetic replacement of the proximal tibia:Different techniques for extensor reconstruction in 17 tumor patients

We analyzed in 17 patients the outcome of various surgical techniques for reconstruction of the extension apparatus after resection of the proximal tibia and tumor prosthesis implantation. The mean follow-up period was 5 (1.5-11) years. Knee extension and flexion strength were measured isokinetically by dynamometer and muscle activities of the vastus medialis, the vastus lateralis and the rectus femoris muscles determined by means of EMG. Muscle function of the operated leg was compared to that of the contralateral extremity by using various surgical techniques: fibula transposition, transposition of the gastrocnemius muscle, and combination technique. The results concerning the operated leg were compared within the 3 groups and the activity and strength of both legs were compared to those of a control group of healthy subjects matched for age and weight. The strength of extensor muscles of the healthy leg was greater than that of the control group in flexion position (60 degrees-90 degrees); the hamstring strength values were within the normal range. The strength of extensor muscles of the operated leg differed between groups II and III at 90 degrees in favor of group II (p < 0.01) and at 60 degrees to 20 degrees (p < 0.001) in favor of group III. Expressed in percentage ranges (nonoperated leg set at 100 percent) the flexor muscles averaged 30 percent, the extensor muscles represented on average 12 percent (9-17 percent) in group I, 9 percent (5-18 percent) in group II and 16 percent (6-26 percent) in group III, depending on the knee angle.(ABSTRACT TRUNCATED AT 250 WORDS)

Time kinetics of acute changes in muscle architecture in response to resistance exercise

OBJECTIVES The study aimed to assess acute changes in muscle architecture and its recovery after exhaustive exercise. We hypothesised that repetitive leg press exercise would decrease vastus lateralis fascicle length, while increasing both muscle thickness and pennation angles. By investigating the time kinetics of recovery of these parameters, we wished to gain insight into the mechanisms responsible for muscle architectural changes during exercise. DESIGN Muscle architecture was assessed in 41 male volunteers (25.2±3.7 yrs; 1.78±0.06 m; 76.4±11.7 kg) before and directly after, as well as 5, 10, 15, and 30 min after induction of fatigue by leg press exercise. METHOD Vastus lateralis muscle thickness, pennation angles and fascicle lengths were measured at rest by ultrasonography. Muscular fatigue was induced by an exhaustive series of maximum power, single leg press repetitions. RESULTS Following leg press exercise vastus lateralis muscle thickness and pennation angles were increased by approximately 7 and 10%, whereas fascicle lengths decreased by 2%. Different recovery times (muscle thickness: 30 min; pennation angles: 15 min; fascicle lengths: 5 min) were observed. CONCLUSIONS The differential time courses of recovery suggest that changes in muscle thickness, pennation angles, and fascicle lengths are driven by different exercise-related stimuli. Increased muscle perfusion and tendon creep are likely candidates accounting for short-term changes in muscle architecture.

Respiratory gas exchange and lactate measures during competitive orienteering.

PURPOSE In the past, orienteering sports analyses were based on heart rate (HR) and lactate (LA) measures. This study assessed additional respiratory gas exchange measures (RGEM) to provide further information regarding the physiological requirements of orienteering competitions (OTC). METHODS Eleven elite male athletes performed simulated OTC. RGEM were performed using a portable system. LA was determined after each section (total of six) of OTC. Athletes were also subjected to treadmill testing (TT). RESULTS Average values for the entire OTC were [OV0312]O(2OTC): 56.4 +/- 4.5 mL.kg-1.min-1 (83.0 +/- 3.8% of [OV0312]O(2max) of TT), HR(OTC): 172 +/- 11 bpm, and LA(OTC): 5.16 +/- 1.5 mmol.L-1. The highest measured [OV0312]O(2OTC) of an athlete in this study was 64.4 +/- 2.9 mL.kg-1.min-1. [OV0312]O(2OTC) was 94.6 +/- 5.2% of [OV0312]O(2IAT) (IAT= individual anaerobic threshold), HR(OTC) was 98.0 +/- 2.9% of HR(IAT), respiratory exchange ratio was 97 +/- 3.8% and LA(OTC) was 143.9 +/- 24.2% of LA(IAT). In contrast to [OV0312]O(2) and LA, average HR were similar in all sections of OTC despite topographical differences of the course. No correlations were found between running time of OTC and variables of endurance performance. Running time correlated with running distance (P < 0.001; r = 0.83) and running speed (r = 0.98; P < 0.001). CONCLUSION 1) Energy requirements during OTC were derived predominately via aerobic metabolism. 2) The highest [OV0312]O(2OTC) value of 64.4 mL.kg-1.min-1 may be regarded as the reference for intensities of OTC. 3) During OTC, most athletes avoid high-intensity periods of long duration. 4) Performance in OTC was essentially influenced by technical abilities. 5) Using only LA for evaluation may lead to overestimation of energy demands during OTC. 6) HR measures were not sufficiently sensitive to ascertain energy requirements of the OTC. Therefore, RGEM provided additional information regarding energy expenditure of OTC compared with LA and HR measures alone.

THE HEART RATE TURN POINT RELIABILITY AND METHODOLOGICAL ASPECTS

PURPOSE The aim of the study was to test protocol variations on the heart rate performance curve (HRPC) and the heart rate turn point (HRTP) according to Conconi et al. (1996). Respiratory gas exchange variables were used to define three phases of energy supply (I, II, III). METHODS Eighteen healthy young male subjects performed 4 tests (T1-T4). T1: initial speed of 6 km x h(-1) followed by increments of 0.6 km x h(-1) every 60 s. Subjects were than randomized for the next three tests. T2: initial speed 5.6 km x h(-1) followed by increments of 0.2 km x h(-1) every 20 s; T3: similar to T2, in the second half of phase III acceleration (S) was increased. T4: like T2, at the beginning of phase III, S was increased. No differences were found in the degree of the deflection of the HRPC expressed as factor kHR between T1 (0.228 +/- 0.225) and T2 (0.248 +/- 0.231) but a significant increase was found in T3 (0.533 +/- 0.248) and T4 (0.770 +/- 0.258). RESULTS The modifications of the protocol (T3 and T4) systematically influenced the deflection of the HRPC, but kHR was highly reproducible in all tests. Eleven subjects showed degrees of deflection in the HRPC in all tests. There were no significant differences for S, HR, and VO2 at the HRTP. An HRTP was not found in seven subjects in neither T1 or T2; however, in T3 and T4, these seven subjects showed a deflection of HRPC resulting from the protocol. The HRTP was found to be dependent on the start of the acceleration in phase III. In cases with a linear time course in the HRPC in T1 and T2, in T3 an HRTP was found at 15.6 km x h(-1) and in T4 at 13.6 km x h(-1) , respectively. CONCLUSION The Conconi test protocol with an accelerated increase in S in the final phase of the test has a major influence on the occurrence of the HRTP in cases of near linear HRPC.

Functional performance in community-dwelling and institutionalized elderly women

ZusammenfassungZIELE: Der hohe Stellenwert körperlicher Aktivität für die Gesundheit und Mobilität im höheren Alter gilt als hinreichend belegt. Aktuelle Studien lassen einen Zusammenhang zwischen dem Lebensumfeld und dem körperlichen Aktivitätsniveau älterer Menschen vermuten. In der vorliegenden Untersuchung wurden daher die muskuläre Leistungsfähigkeit der oberen Extremität, die Gleichgewichtsfähigkeit und Reaktionszeit von selbständigen und im Heim lebenden Seniorinnen untersucht. METHODEN: Insgesamt 31 Probandinnen im Alter von 77–86 Jahren nahmen an der Untersuchung teil. Die Unterschiede zwischen dem selbständigen und im Heim lebenden Kollektiv bezüglich Alter, Größe, Gewicht und BMI waren durchwegs nicht signifikant (p > 0,05). Messungen der muskulären Leistungsfähigkeit der Oberarmflexoren, ein Gleichgewichtstest sowie ein komplexer Reaktionstest wurden durchgeführt. Die muskuläre Leistung wurde mit Hilfe von Kurzhanteln unterschiedlicher Masse (0,5, 1, 1,5, und 2 kg) ermittelt. Mit Hilfe eines Fragebogens wurden der tägliche Zeitaufwand für körperliche Aktivitäten sowie die Arten der ausgeübten körperlichen Aktivitäten erhoben. ERGEBNISSE: Die selbständig lebenden Probandinnen schnitten sowohl bei den Untersuchungen der muskulären Leistung (p ≤ 0,002) als auch beim Reaktionstest (p = 0,014) signifikant besser ab. Die Unterschiede in der Gleichgewichtsfähigkeit erreichten jedoch keine statistische Signifikanz (p = 0,086). Sowohl die täglichen Gehzeiten (p = 0,002) als auch der Zeitaufwand für weitere körperliche Aktivitäten (p = 0,017) waren bei den selbständig lebenden Probandinnen deutlich größer. DISKUSSION: Auf Basis unserer Ergebnisse schließen wir, dass sich selbständiges Leben im hohen Alter positiv auf die muskuläre Leistungsfähigkeit sowie die Reaktionsfähigkeit auswirkt. Zur Überprüfung der Gleichgewichtsfähigkeiten in dieser Altersgruppe sollten sichere und einfache Testsysteme entwickelt werden. Das körperliche Aktivitätsniveau war in der Gruppe der selbständig lebenden Teilnehmerinnen größer. Es ist jedoch unklar, ob die geringere Aktivität Ursache oder Folge des Lebens im Altersheim ist.SummaryOBJECTIVES: Previous reports have underlined the importance of physical activity for physical functioning in older age. As recent results suggest that living in nursing homes is negatively correlated to physical activity level, this survey examined whether muscular power, balance abilities and response times differ between community-dwelling and institutionalized old women. METHODS: A sample of 31 community-dwelling and institutionalized women aged 77–86 years was recruited. Groups did not differ in age, weight, height, or BMI (p > 0.05). Measurements of upper limb power, balance control, and response time were conducted. Upper limb power was tested by dumbbell biceps curl exercise with increasing loads (0.5, 1, 1.5, and 2 kg). Overall daily time expenditure for walking and further physical activities as well as kinds of further activities were examined via questionnaire. RESULTS: The community-dwelling subjects achieved significantly better results in tests of upper limb power and response time (p ≤ 0.002 and = 0.014) than the institutionalized participants. No significant differences were found in balance control (p = 0.086). Both daily walking time and time for further physical activities were higher in community-dwelling subjects (p = 0.002 and 0.017). CONCLUSIONS: Based on our findings we conclude that independent lifestyle may contribute to higher muscular power and faster response times in older age. To analyze balance abilities in this age group safe and easy to use laboratory testing devices should be developed. We found physical activity levels to be higher in the community-dwelling cohort. However, we do not know whether reduced physical activity is the cause or rather the consequence of institutionalized living.

Assessment of metabolic response and functional changes after anterior cruciate ligament surgery

The main purpose of this study was to investigate metabolic changes after anterior cruciate ligament reconstruction and to find out whether the statements on training intensity in the literature can also be applied to patients in rehabilitation. Twenty-four male patients, 16 wk (range: 11-21 wk) postoperative, volunteered to participate in the study. A new four-stage test with constant time and load increments on the legpress in the closed kinetic chain (CKC) was performed. Evaluative variables were the aerobic and anaerobic threshold, force at exhaustion, and the maximum strength. Besides the four-stage test, the other parameters evaluated were functional tests (one-legged single hop, one-legged triple hop), rating scales (Lysholm, subjective feeling scale), thigh circumference, peak torque (PT), work and explosive force in the open kinetic chain (OKC), and muscle activity via electromyographic examination. Positive correlations were established for the maximum force in the CKC and PT (P < 0.01) and maximum force in the CKC and the thigh circumference (P < 0.05). The Lysholm score correlated with the anaerobic threshold (P < 0.05) and with the functional tests (P < 0.01). Further correlations were established between the PT and the work (P < 0.05) and between the single hop and the triple hop (P < 0.001). While the maximum force of the uninvolved leg was significantly higher than that of the involved leg (P < 0.01), the forces measured at termination and at the aerobic and anaerobic threshold (given as percent of maximum force) were significantly higher in the involved leg (P < 0.01). It seems that the oxidative potential increases or remains constant in this phase of rehabilitation and therefore the intensity of strength training must be adapted to the needs of the patient. Our easy-to-perform method makes it possible to establish an optimal intensity of training.

Concentric and Eccentric Exercise Testing — A new Approach to a Four Extremities Ergometer

It is a very important and well known task of ergometry, to evaluate the physiological response of the working organism depending on different load regimen. The interpretation of the metabolic cardiopulmonary and neuromuscular response of a given workload requires an exact physical definition of the power output of the working muscles. This includes the standardization of muscular action depending on the movement range and angle-velocity to get both reliable and valid results. Furthermore it is necessary to provide exact measurements of the force and force-velocity relationship during exercise.