Cadence Paradox in Cycling-Part 1: Maximal Lactate Steady State and Carbohydrate Utilization Dependent on Cycling Cadence

PURPOSE

To assess (1) whether and how a higher maximal lactate steady state (MLSS) at higher cycling cadence (RPM) comes along with higher absolute and/or fractional carbohydrate combustion (CHOMLSS), respectively, and (2) whether there is an interrelation between potential RPM-dependent MLSS effects and the maximally achievable RPM (RPMMAX).

METHODS

Twelve healthy males performed incremental load tests to determine peak power, peak oxygen uptake, and 30-minute MLSS tests at 50 and 100 per minute, respectively, to assess RPM-dependent MLSS, corresponding power output, CHOMLSS responses, and 6-second sprints to measure RPMMAX.

RESULTS

Peak power, peak carbon dioxide production, and power output at MLSS were lower (P = .000, ω2 = 0.922; P = .044, ω2 > 0.275; and P = .016, ω2 = 0.373) at 100 per minute than at 50 per minute. With 6.0 (1.5) versus 3.8 (1.2) mmol·L-1, MLSS was higher (P = .000, ω2 = 0.771) at 100 per minute than at 50 per minute. No corresponding RPM-dependent differences were found in oxygen uptake at MLSS, carbon dioxide production at MLSS, respiratory exchange ratio at MLSS, CHOMLSS, or fraction of oxygen uptake used for CHO at MLSS, respectively. There was no correlation between the RPM-dependent difference in MLSS and RPMMAX.

CONCLUSIONS

The present study extends the previous finding of a consistently higher MLSS at higher RPM by indicating (1) that at fully established MLSS conditions, respiration and CHOMLSS management do not differ significantly between 100 per minute and 50 per minute, and (2) that linear correlation models did not identify linear interdependencies between RPM-dependent MLSS conditions and RPMMAX.

Energetics of Floor Gymnastics: Aerobic and Anaerobic Share in Male and Female Sub-elite Gymnasts

Background

Artistic gymnastics is a popular Olympic discipline where female athletes compete in four and male athletes in six events with floor exercise having the longest competition duration in Women’s and Men’s artistic gymnastics (WAG, MAG). To date no valid information on the energetics of floor gymnastics is available although this may be important for specific conditioning programming. This study evaluated the metabolic profile of a simulated floor competition in sub-elite gymnasts.

Methods

17 (9 male, 8 female) sub-elite gymnasts aged 22.5 ± 2.6y took part in a floor-training-competition where oxygen uptake was measured during and until 15 min post-exercise. Additionally, resting and peak blood lactate concentration after exercise were obtained. The PCr-LA-O2 method was used to calculate the metabolic energy and the relative aerobic (WAER), anaerobic alactic (WPCr) and anaerobic lactic (WBLC) energy contribution. Further, the athletes completed a 30 s Bosco-jumping test, a countermovement jump and a drop jump.

Results

The competition scores were 9.2 (CI:8.9–9.3) in WAG and 10.6 (CI:10.4–10.9) in MAG. The metabolic profile of the floor routine was mainly aerobic (58.9%, CI: 56.0–61.8%) followed by the anaerobic alactic (24.2%, CI: 21.3–27.1%) and anaerobic lactic shares (16.9%, CI:14.9–18.8%). While sex had a significant (p = .010, d = 1.207) large effect on energy contribution, this was not the case for competition duration (p = .728, d = 0.061). Relative energy contribution of WAG and MAG differed in WAER (64.0 ± 4.7% vs. 54.4 ± 6.8%, p = .004, d = 1.739) but not in WPCr (21.3 ± 6.1% vs. 26.7 ± 8.0%, p = .144, d = 0.801) and WBLC (14.7 ± 5.4% vs. 18.9 ± 4.2%, p = .085, d = 0.954). Further no correlation between any energy share and performance was found but between WPCr and training experience (r = .680, p = .044) and WBLC and competition level (r = .668, p = .049).

Conclusion

The results show a predominant aerobic energy contribution and a considerable anaerobic contribution with no significant difference between anaerobic shares. Consequently, gymnastic specific aerobic training should not be neglected, while a different aerobic share in WAG and MAG strengthens sex-specific conditioning. All in all, the specific metabolic share must secure adequate energy provision, while relative proportions of the two anaerobic pathways seem to depend on training and competition history.

Climbing-Specific Exercise Tests: Energy System Contributions and Relationships With Sport Performance

Purpose

The aim of the study was to evaluate distinct performance indicators and energy system contributions in 3 different, new sport-specific finger flexor muscle exercise tests.

Methods

The tests included the maximal strength test, the all-out test (30 s) as well as the continuous and intermittent muscle endurance test at an intensity equaling 60% of maximal force, which were performed until target force could not be maintained. Gas exchange and blood lactate were measured in 13 experienced climbers during, as well as pre and post the test. The energy contribution (anaerobic alactic, anaerobic lactic, and aerobic) was determined for each test.

Results

The contribution of aerobic metabolism was highest during the intermittent test (59.9 ± 12.0%). During continuous exercise, this was 28.1 ± 15.6%, and in the all-out test, this was 19.4 ± 8.1%. The contribution of anaerobic alactic energy was 27.2 ± 10.0% (intermittent), 54.2 ± 18.3% (continuous), and 62.4 ± 11.3% (all-out), while anaerobic lactic contribution equaled 12.9 ± 6.4, 17.7 ± 8.9, and 18.2 ± 9.9%, respectively.

Conclusion

The combined analysis of performance predictors and metabolic profiles of the climbing test battery indicated that not only maximal grip force, but also all-out isometric contractions are equally decisive physical performance indices of climbing performance. Maximal grip force reflects maximal anaerobic power, while all-out average force and force time integral of constant isometric contraction at 60% of maximal force are functional measures of anaerobic capacity. Aerobic energy demand for the intermittent exercise is dominated aerobic re-phosphorylation of high-energy phosphates. The force-time integral from the intermittent test was not decisive for climbing performance.

Effect of intensive prior exercise on muscle fiber activation, oxygen uptake kinetics, and oxygen uptake plateau occurrence

Purpose

We tested the hypothesis that the described increase in oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2)-plateau incidence following a heavy-severe prior exercise is caused by a steeper increase in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2 and muscle fiber activation in the submaximal intensity domain.

Methods

Twenty-one male participants performed a standard ramp test, a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2max}}}}$$\end{document}V˙O2max verification bout, an unprimed ramp test with an individualized ramp slope and a primed ramp test with the same ramp slope, which was preceded by an intensive exercise at 50% of the difference between gas exchange threshold and maximum workload. Muscle fiber activation was recorded from vastus lateralis, vastus medialis, and gastrocnemius medialis using a surface electromyography (EMG) device in a subgroup of 11 participants. Linear regression analyses were used to calculate the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-(\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta \dot{V}{\text{O}}_{{2}} /\Delta P$$\end{document}ΔV˙O2/ΔP) and EMG-(∆RMS/∆P) ramp test kinetics.

Results

Twenty out of the 21 participants confirmed their \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2max}}}}$$\end{document}V˙O2max in the verification bout. The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-plateau incidence in these participants did not differ between the unprimed (n = 8) and primed (n = 7) ramp test (p = 0.500). The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta \dot{V}{\text{O}}_{{2}} /\Delta P$$\end{document}ΔV˙O2/ΔP was lower in the primed compared to the unprimed ramp test (9.40 ± 0.66 vs. 10.31 ± 0.67 ml min⁻¹ W⁻¹, p < 0.001), whereas the ∆RMS/∆P did not differ between the ramp tests (0.62 ± 0.15 vs. 0.66 ± 0.14% W⁻¹; p = 0.744).

Conclusion

These findings do not support previous studies, which reported an increase in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-plateau incidence as well as steeper increases in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2 and muscle fiber activation in the submaximal intensity domain following a heavy-severe prior exercise.

Size-adjusted muscle power and muscle metabolism in patients with cystic fibrosis are equal to healthy controls - a case control study

Background

Skeletal muscle function dysfunction has been reported in patients with cystic fibrosis (CF). Studies so far showed inconclusive data whether reduced exercise capacity is related to intrinsic muscle dysfunction in CF.

Methods

Twenty patients with CF and 23 age-matched controls completed an incremental cardiopulmonary cycling test. Further, a Wingate anaerobic test to assess muscle power was performed. In addition, all participants completed an incremental knee-extension test with ³¹P magnetic resonance spectroscopy to assess muscle metabolism (inorganic phosphate (Pi) and phosphocreatinine (PCr) as well as intracellular pH). In the MRI, muscle cross-sectional area of the M. quadriceps (qCSA) was also measured. A subgroup of 15 participants (5 CF, 10 control) additionally completed a continuous high-intensity, high-frequency knee-extension exercise task during ³¹P magnetic resonance spectroscopy to assess muscle metabolism.

Results

Patients with CF showed a reduced exercise capacity in the incremental cardiopulmonary cycling test (VO₂peak: CF 77.8 ± 16.2%predicted (36.5 ± 7.4 ml/qCSA/min), control 100.6 ± 18.8%predicted (49.1 ± 11.4 ml/qCSA/min); p < 0.001), and deficits in anaerobic capacity reflected by the Wingate test (peak power: CF 537 ± 180 W, control 727 ± 186 W; mean power: CF 378 ± 127 W, control 486 ± 126 W; power drop CF 12 ± 5 W, control 8 ± 4 W. all: p < 0.001). In the knee-extension task, patients with CF achieved a significantly lower workload (p < 0.05). However, in a linear model analysing maximal work load of the incremental knee-extension task and results of the Wingate test, respectively, only muscle size and height, but not disease status (CF or not) contributed to explaining variance. In line with this finding, no differences were found in muscle metabolism reflected by intracellular pH and the ratio of Pi/PCr at submaximal stages and peak exercise measured through MRI spectroscopy.

Conclusions

The lower absolute muscle power in patients with CF compared to controls is exclusively explained by the reduced muscle size in this study. No evidence was found for an intrinsic skeletal muscle dysfunction due to primary alterations of muscle metabolism.

Oxygen uptake plateau occurrence depends on oxygen kinetics and oxygen deficit accumulation

We tested the hypothesis that participants with an oxygen uptake ( V ˙ O 2 ) plateau during incremental exercise exhibit a lower VO₂ -deficit (VO_2DEF )-accumulation in the submaximal intensity domain due to faster ramp and square wave O₂ -kinetics. Twenty-six male participants performed a standard ramp test (increment: 30 W·min^-1 ), a ramp test with an individualized ramp slope and a two-step (moderate and severe) square wave exercise followed by a V ˙ O 2 m a x -verification bout. VO_2DEF was calculated by the difference between individualized ramp test V ˙ O₂ and V ˙ O₂ -demand estimated from steady-state V ˙ O₂ -kinetics. Twenty-four participants verified their V ˙ O_2max in the verification test. Ten of them showed a plateau in the individualized ramp test. VO_2DEF at the end of this ramp test (4.34 ± 0.60 vs 4.54 ± 0.43 L) was not different between the plateau and the non-plateau group (P > 0.05). The plateau group had a significantly (P < 0.05) lower VO_2DEF 2 minutes before termination of the individualized ramp test (2.24 ± 0.40 vs 2.78 ± 0.33 L). This coincided with a shorter mean response time (43 ± 9 vs 53 ± 7 seconds), a higher increase in V ˙ O₂ per W (10.1 ± 0.2 vs 9.2 ± 0.5 mL·min^-1 ·W^-1 ) at the individualized ramp test as well as shorter time constants of moderate (36 ± 6 vs 48 ± 7 seconds) and severe (62 ± 9 vs 86 ± 10 seconds) square wave kinetics (all P < 0.05). We conclude that the V ˙ O₂ -plateau occurrence requires a fast V ˙ O₂ -kinetics and a low VO_2DEF -accumulation at intensities below V ˙ O_2max .

Higher energy and carbohydrate demand of interval training at a given average velocity on track versus treadmill

We tested the hypothesis that because of acceleration and deceleration, the energy and carbohydrate demand are higher in interval training on a track than on a treadmill. Ten male subjects performed the same interval training on a treadmill and an outdoor track. A higher energy and carbohydrate demand on the track emphasizes that treadmill interval studies analyzing high numbers of short-lasting interval bouts are not transferable to interval running on a track.

Table tennis playing styles require specific energy systems demands

The aim of the present study was to investigate the differences in energy system contributions and temporal variables between offensive and all-round playing styles. Fifteen male table tennis players (Offensive players: N = 7; All-round players: N = 8) participated in the study. Matches were monitored by a portable gas analyzer and the blood lactate responses was also measured. The contributions of the oxidative (WOXID), phosphagen (WPCr), and glycolytic (W[La]) energy systems were assumed as the oxygen consumption measured during the matches above of baseline value, the fast component of excess post-exercise oxygen consumption (EPOCFAST) measured after the matches, and the net of blood lactate concentration (Δ[La]), respectively. Energy systems contributions were not significantly different between the offensive and all-round playing styles (WOXID: 96.1±2.0 and 97.0±0.6%, P = 0.86; WPCr: 2.7±1.7 and 2.0±0.6%, P = 0.13; W[La]: 1.2±0.5 and 1.0±0.7%, P = 0.95; respectively), however, magnitude-based analysis of WPCr presented Likely higher contribution for offensive compared to all-round players. Regarding temporal variables, only rate of shots presented higher values for offensive when compared to all-round players (P = 0.03), while the magnitude-based analysis presented Very likely lower, Likely lower and Likely higher outcomes of rate of shots, WPCr and maximal oxygen consumption, respectively, for all-round players. Strong negative correlation was verified for offensive players between number of shots and WPCr (r = -0.86, P = 0.01), while all-round players showed strong correlations between rally duration, WOXID (r = 0.76, P = 0.03) and maximal oxygen consumption (r = 0.81, P = 0.03). Therefore, despite no differences in energy system contributions for offensive and all-round players, different playing styles seems to requires specific energy systems demands.

[Recommendations for Physical Activity and Sedentary Behaviour for Children and Adolescents: Methods, Database and Rationale]

The benefits of physical activity and a reduction of sedentary behaviour in childhood and adolescence are well established.Based on a quality-assured literature review, the German recommendations were updated. Guidelines for infants, toddlers, children of kindergarten and primary school age and youth are clearly depictedIn general, a higher amount of physical activity is associated with more health benefits. Preschool age children should have 180 min of physical activity daily, and from primary school age on, at least 90 min daily are recommended. Sedentary behaviour, especially time in front of screens, is to be reduced to a minimum.

Caffeine Affects Time to Exhaustion and Substrate Oxidation during Cycling at Maximal Lactate Steady State

This study analyzed the effects of caffeine intake on whole-body substrate metabolism and exercise tolerance during cycling by using a more individualized intensity for merging the subjects into homogeneous metabolic responses (the workload associated with the maximal lactate steady state—MLSS). MLSS was firstly determined in eight active males (25 ± 4 years, 176 ± 7 cm, 77 ± 11 kg) using from two to four constant-load tests of 30 min. On two following occasions, participants performed a test until exhaustion at the MLSS workload 1 h after taking either 6 mg/kg of body mass of caffeine or placebo (dextrose), in a randomized, double-blinded manner. Respiratory exchange ratio was calculated from gas exchange measurements. There was an improvement of 22.7% in time to exhaustion at MLSS workload following caffeine ingestion (95% confidence limits of ±10.3%, p = 0.002), which was accompanied by decrease in respiratory exchange ratio (p = 0.001). These results reinforce findings indicating that sparing of the endogenous carbohydrate stores could be one of the several physiological effects of caffeine during submaximal performance around 1 h.

High cycling cadence reduces carbohydrate oxidation at given low intensity metabolic rate

Cycling cadence (RPM)-related differences in blood lactate concentration (BLC) increase with increasing exercise intensity, whilst corresponding divergences in oxygen uptake (V.O₂) and carbon dioxide production (V.CO₂) decrease. Aim of the present study was to test whether a higher RPM reduces the fraction (%) of the V.O₂ used for carbohydrate oxidation (relCHO) at a given BLC. Eight males (23.9 ± 1.6 yrs; 177 ± 3 cm; 70.3 ± 3.4 kg) performed incremental load tests at 50 and 100 RPM. BLC, V.O₂ and V.CO₂ were measured. At respiratory exchange ratios (RER) < 1, relCHO were calculated and the constant determining 50 % relCHO (k_CHO) was approximated as a function of the BLC. At submaximal workload V.O₂, V.CO₂, and relCHO were lower (all p < 0.002; η² > 0.209) at 50 than at 100 RPM. No differences were observed in V.O₂peak (3.96 ± 0.22 vs. 4.00 ± 0.25 l · min⁻¹) and RER_peak (1.18 ± 0.02 vs. 1.15 ± 0.02). BLC was lower (p < 0.001; η² = 0.680) at 50 than at 100 RPM irrespective of cycling intensity. At 50 RPM, kCHO (4.2 ± 1.4 (mmol · l⁻¹)³) was lower (p = 0.043; η² = 0.466) than at 100 RPM (5.9 ± 1.9 (mmol · l⁻¹)³). This difference in k_CHO reflects a reduced CHO oxidation at a given BLC at 100 than at 50 RPM. At a low exercise intensity, a higher cycling cadence can substantially reduce the reliance on CHO at a given metabolic rate and/or BLC.

Pilot investigation of the oxygen demands and metabolic cost of incremental shuttle walking and treadmill walking in patients with cardiovascular disease

OBJECTIVE

To determine if the metabolic cost of the incremental shuttle-walking test protocol is the same as treadmill walking or predicted values of walking-speed equations.

SETTING

Primary care (community-based cardiac rehabilitation).

PARTICIPANTS

Eight Caucasian cardiac rehabilitation patients (7 males) with a mean age of 67±5.2 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

Oxygen consumption, metabolic power and energy cost of walking during treadmill and shuttle walking performed in a balanced order with 1 week between trials.

RESULTS

Average overall energy cost per metre was higher during treadmill walking (3.22±0.55 J kg/m) than during shuttle walking (3.00±0.41 J kg/m). There were significant post hoc effects at 0.67 m/s (p<0.004) and 0.84 m/s (p<0.001), where the energy cost of treadmill walking was significantly higher than that of shuttle walking. This pattern was reversed at walking speeds 1.52 m/s (p<0.042) and 1.69 m/s (p<0.007) where shuttle walking had a greater energy cost per metre than treadmill walking. At all walking speeds, the energy cost of shuttle walking was higher than that predicted using the American College of Sports Medicine walking equations.

CONCLUSIONS

The energetic demands of shuttle walking were fundamentally different from those of treadmill walking and should not be directly compared. We warn against estimating the metabolic cost of the incremental shuttle-walking test using the current walking-speed equations.

Hemoglobin oxygen affinity in patients with cystic fibrosis

In patients with cystic fibrosis lung damages cause arterial hypoxia. As a typical compensatory reaction one might expect changes in oxygen affinity of hemoglobin. Therefore position (standard half saturation pressure P₅₀st) and slope (Hill’s n) of the O₂ dissociation curve as well as the Bohr coefficients (BC) for CO₂ and lactic acid were determined in blood of 14 adult patients (8 males, 6 females) and 14 healthy controls (6 males, 8 females). While Hill’s n amounted to approximately 2.6 in all subjects, P₅₀st was slightly increased by 1mmHg in both patient groups (controls male 26.7±0.2, controls female 27.0±0.1, patients male 27.7±0.5, patients female 28.0±0.3 mmHg; mean and standard error, overall p<0.01). Main cause was a rise of 1–2 µmol/g hemoglobin in erythrocytic 2,3-biphosphoglycerate concentration. One patient only, clearly identified as an outlier and with the mutation G551D, showed a reduction of both P₅₀st (24.5 mmHg) and [2,3-biphosphoglycerate] (9.8 µmol/g hemoglobin). There were no differences in BCCO₂, but small sex differences in the BC for lactic acid in the controls which were not detectable in the patients. Causes for the right shift of the O₂ dissociation curve might be hypoxic stimulation of erythrocytic glycolysis and an increased red cell turnover both causing increased [2,3-biphosphoglycerate]. However, for situations with additional hypercapnia as observed in exercising patients a left shift seems to be a more favourable adaptation in cystic fibrosis. Additionally when in vivo PO₂ values were corrected to the standard conditions they mostly lay left of the in vitro O₂ dissociation curve in both patients and controls. This hints to unknown fugitive factors influencing oxygen affinity.

Recommendations for promoting physical activity for children and adolescents in Germany. A consensus statement

Increasing physical activity and reduction of sedentary behaviour play important roles in health promotion and prevention of lifestyle-related diseases in children and adolescents. However, the question of how much physical activity is useful for which target group is still a matter of debate. International guidelines (World Health Organization; European Association for the Study of Obesity), which are mainly based on expert opinions, recommend 60 min of physical activity every day. Age- and sex-specific features and regional differences are not taken into account. Therefore, expert consensus recommendations for promoting physical activity of children and adolescents in Germany were developed with special respect to national data, but also with respect to aspects of specific target groups, e.g., children with a lower socio-economic status (SES) or with migration background. They propose 90 min/day of physical activity, or at least 12,000 steps daily. Additionally, lifestyle factors, especially restriction of media consumption, were integrated. The recommendations provide orientation for parents and caregivers, for institutions such as schools and kindergartens as well as for communities and stakeholders.

Long-Range Correlations and Complex Regulation of Pacing in Long-Distance Road Racing

Purpose: To analyse time domain, spectral and fractal properties of speed regulation during half-marathon racing. Methods: In twenty-one male experienced runners high-resolution data on speed (V), stride frequency (SF) and stride length (SL) were assessed during half-marathon competition (21098 m). Performance times, time and frequency domain variability, spectral scaling exponent (beta) and fractal dimension (FD) of V, SF and SL were analysed. Results: V of 3.65±0.41 m·s-1, SF of 1.41±0.05 Hz and SL of 2.58±0.25 m occurred with higher (p<0.05) individual variability in V and SL compared to SF. Beta and FD were always in between 1.04 and 1.88 and 1.56 to 1.99, respectively. Beta and FD differed (p<0.05) in SF and SL compared to V and were correlated in V and SL (r=0.91, p<0.05). Spectral peaks of V, SF and SL occurred at wavelengths in between 3 to 35 min, and those of V and SL were interrelated (r=0.56, p<0.05). Mean SF and mean SL were significantly correlated with performance (r=0.59 and r=0.95, p<0.05). SL accounted for 84±6 % and SF for 16±6 % of speed variability, respectively. Conclusions: The observed non-random fluctuations in V, SF and SL correspond to non-stationary fractional Brownian motion with inherent long-range correlations. This indicates a similar complex regulation process in experienced runners that is primarily mediated via SL.

[Cost evaluation of a model for integrated care of seriously mentally ill patients]

BACKGROUND

The model for integrated care (IC) of those seriously mentally ill patients insured with the DAK-Gesundheit health insurance and various Betriebskrankenkassen (members of the VAG Mitte) from the regions Berlin, Brandenburg, Lower Saxony and Bremen allows a complex treatment in the outpatient setting which consists of psychiatrists, general practitioners and clinicians, psychiatric nursing, sociotherapy (only in Berlin), internal medicine quality circles, orientation on treatment guidelines and conceptual consensus with the relevant care clinics. The aim of the evaluation is to illustrate the health economic effects of IC.

METHODS

In the period from 2006 to 2010 insured members of the DAK-Gesundheit and other involved health insurance companies with a serious mental illness, a significant impairment of social functioning and the need to be treated to avoid or substitute an in-hospital stay were included in the integrated care. The cost perspective was that of the statutory health insurance companies. For the health economic evaluation, the utilisation of continuous IC over 18 months was compared to the last 18 months prior to the inclusion in IC. The clinical findings were gathered quarterly during the IC using CGI (Clinical Global Impressions) and GAF (Global Assessment of Functioning Scale).

RESULTS

A total of 1 364 patients receiving IC in 66 doctor's practices were documented (of those, 286 had diagnoses of ICD-10 F2, 724 ICD-10 F32-F39). The median age was 48.8 years, 69% were female. 24% had their own source of income, 40% were on the pension, and the rest of the patients were receiving transfer benefits in some form. In 54% of the cases IC was used to avoid an in-hospital stay, in 46% of the cases to substitute an in-hospital stay. The degree of the CGI was 5.5 on average at the time of inclusion and the GAF score was 36.5 on average. The 226 patients with continuous documentation over 18 months were included in the health economic analysis. The number of days spent in hospital was lower during the IC period as compared to the 18 months prior to IV (11.8 vs. 28.6 days, p<0.001), the inpatient costs were lower (5 929 ± 13 837 Euro vs. 2 458 ± 6 940 Euro, p<0.001), the total was not significantly changed (7 777 ± 14 263 Euro vs. 7 321 ± 7 910 Euro, p=0.65). The substantial reduction of inpatient costs was compensated by the additional costs for medication and the costs of the complex outpatient care. Results were comparable for the 2 subgroups of schizophrenic/schizoaffective (n=66, 40.9 vs. 17.9 days, p=0.03; inpatient cost 9 009 ± 15 677 Euro vs. 3 650 ± 8 486 Euro, p=0.02; total expenditures 11 789 ± 15 975 Euro vs. 9 623 ± 9 262 Euro, p=0.33) and unipolar depressive patients (n=90, 29.8 vs. 9.8 days, p=0.006; inpatient cost 5 664 ± 14 921 Euro vs. 1 967 ± 5 276 Euro, p=0.02; total expenditures 7 146 ± 15 164 Euro vs. 6 234 ± 6 292 Euro, p=0.57).

CONCLUSION

The IC was able to considerably reduce the utilisation of inpatient treatment through offering a complex range of services in the outpatient setting and allowed for a weight-shift in a low-threshold comprehensive care structure without an increase in costs from the statutory health insurance companies' perspective. For a detailed description of clinical effects further studies are required.

Sports behaviour among HIV-infected versus non-infected individuals in a Berlin cohort

Physical activity has been recommended based on beneficial effects described in HIV-infected patients. However, such guidelines do not take into account actual sport behaviours and general attitudes towards physical activity. To evaluate actual sport activity and attitudes towards sport in HIV-infected versus non-infected individuals we conducted an anonymous questionnaire investigating the prevalence, as well as possible changes, in sports engagement and the overall attitude to physical activity. A total of 283 patients of a general care facility specialized in the treatment of HIV/AIDS in Berlin, Germany, participated; 124 were HIV infected and 159 were non-infected, mostly men who have sex with men (MSM) (88%), with a median age of 35 years. The HIV-infected participants had a median CD4+ count of 554 cells/µL and 48.8% of them were using antiretroviral therapy (ART) at the time of survey. The proportion of patients actually performing physical activity was significantly lower (P = 0.028) within the HIV-infected group (61.3%) than within the non-infected group (74.2%). This difference remained significant after accounting for possible confounders such as age, gender, injecting drug use and sexual preferences. Previously reported sport activity prevalence was similar in both groups on leaving school. From our data we could not identify an association between the time of HIV diagnosis and changes in sports activity. In conclusion, fewer HIV-infected individuals report physical activity than non-infected individuals. Sociodemographic studies to evaluate potential differences in sports behaviour are required in order to inform exercise guidelines for HIV-infected patients.

Metabolic and performance effects of warm-up intensity on sprint cycling

Warm-up is generally considered beneficial for performance, although the reduction in anaerobic glycolytic metabolism may be detrimental to sprinting. This study examined the effect of warm-up intensity on metabolism and performance in sprint cycling. The mean power was determined during a 1-min sprint on 11 trained males preceded by easy (WE), moderate (WM) or hard (WH) warm-up and a 10-min recovery. Aerobic, anaerobic glycolytic and phosphocreatine energy provision to the sprint was determined from oxygen uptake and lactate production. Blood lactate concentration before the sprint increased with the warm-up intensity (WE: 1.2±0.3; WM: 2.0±0.3; WH: 4.2±0.9 mmol/L, P<0.001), with WH reducing the increase in lactate production during exercise vs WE (WE: 11.6±1.6; WM: 10.9±1.9; WH: 9.2±1.4 mmol/L, P<0.05). Despite the lower relative anaerobic glycolytic energy provision in WH vs WE (WH: 38±5; WM: 36±6; WE: 34±3%, P<0.05), the mean power was unaffected (WE: 516±28; WM: 521±26; WH: 526±34 W, P>0.05) due to increased oxygen uptake in WH during the sprint (WE: 3.2±0.4; WM: 3.3±0.3; WH: 3.4±0.4 liters, P<0.05). This study supports a warm-up-induced reduction in glycolytic rate, although sprint performance, at least of a long duration, may be maintained due to increased oxygen utilization.