Exercise responses to in-line skating: comparisons to running and cycling

Capturing the Complex Relationship Between Internal and External Training Load: A Data-Driven Approach

BACKGROUND

Training load is typically described in terms of internal and external load. Investigating the coupling of internal and external training load is relevant to many sports. Here, continuous kernel-density estimation (KDE) may be a valuable tool to capture and visualize this coupling.

AIM

Using training load data in speed skating, we evaluated how well bivariate KDE plots describe the coupling of internal and external load and differentiate between specific training sessions, compared to training impulse scores or intensity distribution into training zones.

METHODS

On-ice training sessions of 18 young (sub)elite speed skaters were monitored for velocity and heart rate during 2 consecutive seasons. Training session types were obtained from the coach's training scheme, including endurance, interval, tempo, and sprint sessions. Differences in training load between session types were assessed using Kruskal-Wallis or Kolmogorov-Smirnov tests for training impulse and KDE scores, respectively.

RESULTS

Training impulse scores were not different between training session types, except for extensive endurance sessions. However, all training session types differed when comparing KDEs for heart rate and velocity (both P < .001). In addition, 2D KDE plots of heart rate and velocity provide detailed insights into the (subtle differences in) coupling of internal and external training load that could not be obtained by 2D plots using training zones.

CONCLUSION

2D KDE plots provide a valuable tool to visualize and inform coaches on the (subtle differences in) coupling of internal and external training load for training sessions. This will help coaches design better training schemes aiming at desired training adaptations.

Assessment of maximal fat oxidation during exercise: A systematic review

Maximal fat oxidation during exercise (MFO) and the exercise intensity eliciting MFO (Fat_max ) are considered biological markers of metabolic health and performance. A wide range of studies have been performed to increase our knowledge about their regulation by exercise and/or nutritional intervention. However, numerous data collection and analysis approaches have been applied, which may have affected the MFO and Fat_max estimation. We aimed to systematically review the available studies describing and/or comparing different data collection and analysis approach factors that could affect MFO and Fat_max estimation in healthy individuals and patients. Two independent researchers performed the search. We included all original studies in which MFO and/or Fat_max were estimated by indirect calorimetry through an incremental graded exercise protocol published from 2002 to 2019. This systematic review provides key information about the factors that could affect MFO and Fat_max estimation: ergometer type, metabolic cart used, warm-up duration and intensity, stage duration and intensities imposed in the graded exercise protocol, time interval selected for data analysis, stoichiometric equation selected to estimate fat oxidation, data analysis approach, time of the day when the test was performed, fasting time/previous meal before the test, and testing days for MFO/Fat_max and maximal oxygen uptake assessment. We suggest that researchers measuring MFO and Fat_max should take into account these key methodological issues that can considerably affect the accuracy, validity, and reliability of the measurement. Likewise, when comparing different studies, it is important to check whether the above-mentioned key methodological issues are similar in such studies to avoid ambiguous and unacceptable comparisons.

Oxygen Uptake and Muscle Deoxygenation Kinetics During Skating: Comparison Between Slide-Board and Treadmill Skating

PURPOSE

To compare the oxygen-uptake ([Formula: see text]) kinetics during skating on a treadmill and skating on a slide board and to discuss potential mechanisms that might control the [Formula: see text] kinetics responses during skating.

METHODS

Breath-by-breath pulmonary [Formula: see text] and near-infrared spectroscopy-derived muscle deoxygenated hemoglobin and myoglobin ([HHbMb]) were monitored continuously in 12 well-trained, young, long-track speed skaters. On-transient [Formula: see text] and [HHbMb] responses to skating on a treadmill and skating on a slide board at 80% of the estimated gas exchange threshold were fitted as monoexponential function. The signals were time-aligned, and the individual [HHbMb]-to-[Formula: see text] ratio was calculated as the average value from 20 to 120 s after exercise starts.

RESULTS

The time constants for the adjustment of phase II [Formula: see text] (τ [Formula: see text]) and [HHbMb] (τ [HHbMb]) were low and similar between slide board and treadmill skating (18.1 [3.4] vs 18.9 [3.6] for τ [Formula: see text] and 12.6 [4.0] vs 12.4 [4.0] s for τ [HHbMb]). The [Formula: see text] ratio was not different from 1.0 (P > .05) in both conditions.

CONCLUSIONS

The fast [Formula: see text] kinetics during skating suggest that chronic adaptation to skating might overcome any possible restriction in leg blood flow during low-intensity exercise. The [Formula: see text] ratio values also suggest a good matching of O₂ delivery to O₂ utilization in trained speed skaters. The similar τ [Formula: see text] and τ [HHbMb] values between slide board and treadmill further reinforce the validity of using a slide board for skating testing and training purposes.

Contextualising Maximal Fat Oxidation During Exercise: Determinants and Normative Values

Using a short-duration step protocol and continuous indirect calorimetry, whole-body rates of fat and carbohydrate oxidation can be estimated across a range of exercise workloads, along with the individual maximal rate of fat oxidation (MFO) and the exercise intensity at which MFO occurs (Fatmax). These variables appear to have implications both in sport and health contexts. After discussion of the key determinants of MFO and Fatmax that must be considered during laboratory measurement, the present review sought to synthesize existing data in order to contextualize individually measured fat oxidation values. Data collected in homogenous cohorts on cycle ergometers after an overnight fast was synthesized to produce normative values in given subject populations. These normative values might be used to contextualize individual measurements and define research cohorts according their capacity for fat oxidation during exercise. Pertinent directions for future research were identified.

Validation of a Maximal Incremental Skating Test Performed on a Slide Board: Comparison With Treadmill Skating

PURPOSE

To investigate the criterion validity of a maximal incremental skating test performed on a slide board (SB).

METHODS

Twelve subelite speed skaters performed a maximal skating test on a treadmill and on a SB. Gas exchange threshold (GET), respiratory compensation point (RCP), and maximal variables were determined.

RESULTS

Oxygen uptake ([Formula: see text]) (31.0 ± 3.2 and 31.4 ± 4.1 mL·min^-1·kg^-1), percentage of maximal [Formula: see text] ([Formula: see text]) (66.3 ± 4 and 67.7 ± 7.1%), HR (153 ± 14 and 150 ±12 bpm), and ventilation (59.8 ± 11.8 and 57.0 ± 10.7 L·min^-1) at GET, and [Formula: see text] (42.5 ± 4.4 and 42.9 ± 4.8 mL·min^-1·kg^-1), percentage of [Formula: see text] (91.1 ± 3.3 and 92.4 ± 2.1%), heart rate (HR) (178 ± 9 and 178 ± 6 bpm), and ventilation (96.5 ± 19.2 and 92.1 ± 12.7 L·min^-1) at RCP were not different between skating on a treadmill and on a SB. [Formula: see text] (46.7 ± 4.4 vs 46.4 ±6.1 mL·min^-1·kg^-1) and maximal HR (195 ± 6 vs 196 ± 10 bpm) were not significantly different and correlated (r = .80 and r = .87, respectively; P < .05) between the treadmill and SB. [Formula: see text] at GET, RCP, and [Formula: see text] obtained on a SB were correlated (r > .8) with athletes' best times on 1500 m.

CONCLUSIONS

The incremental skating test on a SB was capable to distinguish maximal ([Formula: see text] and HR) and submaximal ([Formula: see text], % [Formula: see text], HR, and ventilation) parameters known to determine endurance performance. Therefore, the SB test can be considered as a specific and practical alternative to evaluate speed skaters.

Motor unit firing frequency of lower limb muscles during an incremental slide board skating test

This study investigated how the combination of workload and fatigue affected the frequency components of muscle activation and possible recruitment priority of motor units during skating to exhaustion. Ten male competitive speed skaters performed an incremental maximal test on a slide board. Activation of six muscles from the right leg was recorded throughout the test. A time-frequency analysis was performed to compute overall, high, and low frequency bands from the whole signal at 10, 40, 70, and 90% of total test time. Overall activation increased for all muscles throughout the test (p < 0.05 and ES > 0.80). There was an increase in low frequency (90 vs. 10%, p = 0.035, ES = 1.06) and a decrease in high frequency (90 vs. 10%, p = 0.009, ES = 1.38, and 90 vs. 40%, p = 0.025, ES = 1.12) components of gluteus maximus. Strong correlations were found between the maximal cadence and vastus lateralis, gluteus maximus and gluteus medius activation at the end of the test. In conclusion, the incremental skating test lead to an increase in activation of lower limb muscles, but only gluteus maximus was sensitive to changes in frequency components, probably caused by a pronounced fatigue.

Acute physiological responses to recreational in-line skating in young adults

We examined the physiological responses to in-line skating exercise at self-selected paces in recreationally trained adults. Seven men and 10 women performed in-line skating exercise during which oxygen uptake (VO2) and heart rate (HR) were recorded continuously. Ratings of perceived exertion (RPE) and blood lactate concentration were also obtained at the end of exercise. Furthermore, subjects' peak VO2, peak HR, RPE and gas-exchange thresholds were determined in laboratory settings. The average exercise intensity during in-line skating was 90% of peak HR, 67% of peak VO2, 84% of HR reserve and 64% of VO2 reserve. When expressed as RPE and as metabolic equivalents (METs), the average exercise intensity was 13.1 RPE and 9.4 METs. Overall, these indicators of exercise intensity categorise in-line skating at self-selected paces as a vigorous physical activity. Notably, at similar VO2 values, significantly higher HR (174 ± 16 vs. 156 ± 6 bpm; p<0.001) and RPE (13.1 ± 1.4 vs. 11.7 ± 1.4; p=0.019) were observed for in-line skating compared with treadmill running. We conclude that 1. recreational in-line skating induces physiological responses that are sufficient for improving and maintaining cardiovascular fitness in healthy adults, 2. HR- and RPE-based methods for quantifying the exercise intensity during in-line skating may overestimate the actual metabolic load and 3. the derivation of exercise prescriptions for in-line skating should be preferably based on specific (i.e. in-line skating) graded exhaustive exercise test.

Inline Skating for Balance and Strength Promotion in Children during Physical Education

Deficiencies in balance and strength are common in children and they may lead to injuries. This study investigated the effects of inline skating exercise on balance and strength performance in healthy children. Twenty 11–12-year-old children (8 girls, 12 boys) were assigned to an intervention ( n = 10) or a control ( n = 10) group. Participants in the intervention group underwent a 4-week inline skating program (2 times/week, 90 min. each) integrated in their physical education lessons. Balance and strength were measured using the Star Excursion Balance test and the countermovement jump test. As compared to the control group, the intervention group significantly improved balance (17–48%, Cohen's d = 0.00–1.49) and jump height (8%, Cohen's d = 0.48). In children, inline skating is a safe, feasible (90% adherence rate), and effective program that can be integrated in physical education lessons to promote balance and strength.

Cold exposure enhances fat utilization but not non-esterified fatty acids, glycerol or catecholamines availability during submaximal walking and running

Cold exposure modulates the use of carbohydrates (CHOs) and fat during exercise. This phenomenon has mostly been observed in controlled cycling studies, but not during walking and running when core temperature and oxygen consumption are controlled, as both may alter energy metabolism. This study aimed at examining energy substrate availability and utilization during walking and running in the cold when core temperature and oxygen consumption are maintained. Ten lightly clothed male subjects walked or ran for 60-min, at 50% and 70% of maximal oxygen consumption, respectively, in a climatic chamber set at 0°C or 22°C. Thermal, cardiovascular, and oxidative responses were measured every 15-min during exercise. Blood samples for serum non-esterified fatty acids (NEFAs), glycerol, glucose, beta-hydroxybutyrate (BHB), plasma catecholamines, and serum lipids were collected immediately prior, and at 30- and 60-min of exercise. Skin temperature strongly decreased while core temperature did not change during cold trials. Heart rate (HR) was also lower in cold trials. A rise in fat utilization in the cold was seen through lower respiratory quotient (RQ) (-0.03 ± 0.02), greater fat oxidation (+0.14 ± 0.13 g · min(-1)) and contribution of fat to total energy expenditure (+1.62 ± 1.99 kcal · min(-1)). No differences from cold exposure were observed in blood parameters. During submaximal walking and running, a greater reliance on derived fat sources occurs in the cold, despite the absence of concurrent alterations in NEFAs, glycerol, or catecholamine concentrations. This disparity may suggest a greater reliance on intra-muscular energy sources such as triglycerides during both walking and running.

Differences in whole-body fat oxidation kinetics between cycling and running

This study aimed to quantitatively describe and compare whole-body fat oxidation kinetics in cycling and running using a sinusoidal mathematical model (SIN). Thirteen moderately trained individuals (7 men and 6 women) performed two graded exercise tests, with 3-min stages and 1 km h(-1) (or 20 W) increment, on a treadmill and on a cycle ergometer. Fat oxidation rates were determined using indirect calorimetry and plotted as a function of exercise intensity. The SIN model, which includes three independent variables (dilatation, symmetry and translation) that account for main quantitative characteristics of kinetics, provided a mathematical description of fat oxidation kinetics and allowed for determination of the intensity (Fat(max)) that elicits maximal fat oxidation (MFO). While the mean fat oxidation kinetics in cycling formed a symmetric parabolic curve, the mean kinetics during running was characterized by a greater dilatation (i.e., widening of the curve, P < 0.001) and a rightward asymmetry (i.e., shift of the peak of the curve to higher intensities, P = 0.01). Fat(max) was significantly higher in running compared with cycling (P < 0.001), whereas MFO was not significantly different between modes of exercise (P = 0.36). This study showed that the whole-body fat oxidation kinetics during running was characterized by a greater dilatation and a rightward asymmetry compared with cycling. The greater dilatation may be mainly related to the larger muscle mass involved in running while the rightward asymmetry may be induced by the specific type of muscle contraction.

Optimizing fat oxidation through exercise and diet

Interventions aimed at increasing fat metabolism could potentially reduce the symptoms of metabolic diseases such as obesity and type 2 diabetes and may have tremendous clinical relevance. Hence, an understanding of the factors that increase or decrease fat oxidation is important. Exercise intensity and duration are important determinants of fat oxidation. Fat oxidation rates increase from low to moderate intensities and then decrease when the intensity becomes high. Maximal rates of fat oxidation have been shown to be reached at intensities between 59% and 64% of maximum oxygen consumption in trained individuals and between 47% and 52% of maximum oxygen consumption in a large sample of the general population. The mode of exercise can also affect fat oxidation, with fat oxidation being higher during running than cycling. Endurance training induces a multitude of adaptations that result in increased fat oxidation. The duration and intensity of exercise training required to induce changes in fat oxidation is currently unknown. Ingestion of carbohydrate in the hours before or on commencement of exercise reduces the rate of fat oxidation significantly compared with fasted conditions, whereas fasting longer than 6 h optimizes fat oxidation. Fat oxidation rates have been shown to decrease after ingestion of high-fat diets, partly as a result of decreased glycogen stores and partly because of adaptations at the muscle level.

Fat oxidation rates are higher during running compared with cycling over a wide range of intensities

The aim of the present study was to compare the intensity that elicits maximal fat oxidation (Fat(max)) determined using a cycle-ergometer and a treadmill-based protocol. Twelve moderately trained male subjects (66.9 +/- 1.8 mL. kg(-1). min(-1)) performed 2 graded exercise tests to exhaustion. One test was performed on a cycle ergometer while 1 test was performed on a motorized treadmill; stage duration during both trials was 3 minutes. Gas exchange measurements and heart rate (HR) recordings were performed throughout exercise. Fat oxidation rates were calculated using stoichiometric equations. Maximal fat oxidation rates were significantly higher during running compared with cycling (0.65 +/- 0.05 v 0.47 +/- 0.05 g. min(-1)). However, the intensity, which elicited maximal fat oxidation, was not significantly different between the cycle ergometer and treadmill test (62.1 +/- 3.1 v 59.2 +/- 2.8% Vo(2)max, respectively). Fat oxidation rates were significantly higher during the treadmill test compared with the cycle ergometer test from 55 to 80%Vo(2)max. Maximal oxygen uptake and maximal HR were significantly higher during the treadmill test. It was concluded that fat oxidation rates were higher during walking compared with cycling. Maximal fat oxidation was 28% higher when walking compared with cycling, but the intensity, which elicits maximal fat oxidation, is not different between these 2 exercise modes.

Heart rate response and perceived exertion in college students during riding a scooter

The purpose of this research is to examine the heart rate responses and the perceived exertion in college students during scootering, and to examine if scootering possibly makes heart rate increase up to the level that can contribute to maintaining or developing cardiorespiratory fitness. Five male students (20-23 yrs) participated in this research, mainly assigned to scooter on an official 400 m-tartan track. Each session of scootering was six minutes. Each subject did three sessions of scootering at different speeds, slow, ordinary, and very fast. During the scootering, heart rate was measured using a Polar Vantage XL. Immediately after each session, the subjects were questioned about their perceived exertion. To evaluate heart rate during scootering on the track, maximal heart rate was measured in advance with graded maximal tests. In each speed in the track trial, the mean heart rates and the standard deviations were 106 +/- 5.9, 129 +/- 4.2, and 179 +/- 13.7 beats/min respectively. They correspond to 54.0 +/- 4.2%, 65.8 +/- 4.2%, and 91.2 +/- 5.5% of the maximal heart rate respectively. The mean and standard deviation of perceived exertion based on Borg's scale in each scootering session were 7.2 +/- 0.45, 10.2 +/- 1.10, and 16.6 +/- 2.79 respectively. Conclusively, at ordinary speed, the heart rates of the college students on a tartan track were situated around the level of the lower boundary which the American College of Sports Medicine recommended to develop and maintain cardiorespiratory fitness for apparently healthy people. If people have places to ride a scooter briskly, their heart rate could rise above the minimum level.

Comparison between the physiological response to roller skiing and in-line skating in biathletes

PURPOSE

Roller skiing is frequently used in Nordic disciplines during the off-season periods. Recently, in-line skating has become a potential alternative. In the present study, the responses of heart rate, oxygen uptake, respiratory exchange ratio, and lactic acid concentration to roller skiing and in-line skating were compared in competitive biathletes.

METHODS

Eight male subjects performed three tests with both devices on a hilly outdoor track. They were requested to adjust their speed in such a way that the following criteria were met: intensity 1, lactate concentration about 2 mmol x L(-1); intensity 2, lactate concentration about 4 mmol x L(-1); AND intensity 3, maximal speed.

RESULTS

Though the subjects were not experienced in-line skaters, all managed to adjust the required intensities. This was achieved through increased velocities during in-line skating. Independent of the exercise intensity the differences in speed ranged between 1.0 and 1.4 m x s(-1). The relationships between lactic acid concentration, oxygen uptake, respiratory exchange ratio, and heart rate were not influenced by the test device. The respiratory exchange ratio amounted to 0.88, 0.95, and 1.02 for intensities 1 to 3, respectively.

CONCLUSIONS

These results show that in-line skating can be regarded as an alternative to roller skiing for off-seasonal training in Nordic disciplines. A potential advantage of in-line skating is that aerobic training intensities can be obtained at competitive velocities.

Effect of rolling resistance on poling forces and metabolic demands of roller skiing

OBJECTIVE

To examine the effect of an increase in roller ski rolling resistance on the physiological and upper body demands of roller skiing with the V2-alternate technique.

METHODS

Nine highly skilled cross-country skiers roller skied at three paced speeds on a flat oval loop using roller skis with high (HiR) and low (LowR) rolling resistance. Oxygen uptake (VO2), heart rate, and poling forces were measured during the last 30 s and rating of perceived exertion (RPE) was requested immediately after each 4-min bout of roller skiing.

RESULTS

VO2 and all force-related variables increased significantly with speed and were higher (P < 0.01) for HiR at given speeds. Poling time was similar between HiR and LowR, whereas poling recovery time was shorter (P = 0.0002) and cycle rate was higher (P = 0.002) for HiR. For given VO2 levels, peak and average forces, heart rates, and RPE values were similar between HiR and LowR, whereas average poling force across the cycle was greater (P = 0.006) and duty cycle (i.e., percentage of cycle when poling forces were applied) was higher (P = 0.0001) with HiR.

CONCLUSIONS

1) The decrease in poling recovery time and increase in cycle rate associated with an increase in roller ski rolling resistance is comparable to the effect previously observed from increasing grade and probably occurs as a means of limiting deceleration. 2) Since changes in rolling resistance do not alter the relationships of RPE and heart rate with VO2, the central cardiovascular adaptations from roller ski training should not be affected by the rolling resistance of the roller skis. 3) Higher resistance roller skis are likely to induce greater upper body aerobic adaptations than lower resistance roller skis.

Hemoglobin/myoglobin desaturation during speed skating

The characteristic low "sitting" position of competitive speed skating has been shown to result in a right shifted heart rate-VO2 curve and elevated submaximal blood lactate values compared with running or cycling. This is thought to be a consequence of reduced blood flow and subsequent oxygen delivery to the exercising muscle while speed skating. Duel wavelength spectrophotometry was used to measure oxygenated and deoxygenated hemoglobin/myoglobin (OD) in the capillary bed of five muscle groups during in-line skating in upright (US) and low (LS) positions. Eight U.S. speed skaters (4 category 1) performed US and LS at 2.68 and 3.13 m.s-1 (4% grade) on a wide (2.44 m) treadmill (4 trials, 5 min each, 20 min recovery between trials). Expired gas parameters and blood lactate (LA) concentrations were determined for each trial. Hip and knee angles were measured (PEAK Motion Analysis) and were significantly different in US and LS. For similar oxygen uptake during US and LS (44.9 +/- 2.79, 45.6 +/- 3.52), heart rate and LA were significantly higher during LS (172 +/- 11 vs 179 +/- 10, 4.35 +/- 2.19 vs 8.70 +/- 3.60). Deoxygenation was significantly greater during LS than during US at both speeds and was greater at 3.13 m.s-1 (P < 0.05). OD was highly related to LA (r > 0.95) but not to whole body VO2. Blood volume change was less for LS than for US (P < 0.05). Increased deoxygenation in the capillary bed of the exercising quadriceps during LS versus US is consistent with the hypothesis that blood flow and subsequent O2 delivery is compromised in the low speed skating position.

Changes in VO2max and maximal treadmill time after 9 wk of running or in-line skate training

This study tested the hypothesis that running and in-line skating training elicit similar improvements in cardiorespiratory fitness. Changes in maximal oxygen consumption (VO2max) and maximal treadmill endurance time were compared in runners (N = 16), in-line skaters (N = 19), and controls who did no systematic training (N = 7). Training volumes were similar for runners and skaters (3 d.wk-1, 10-40 min/session, 80-90% of exercise specific maximal heart rate) and included both continuous and interval workouts. Pre- and post-training VO2max and maximal treadmill time were measured in all subjects using a running protocol and in skaters using an in-line skating protocol. The groups did not differ in pre-training running VO2max or maximal treadmill time. After 9 wk, significant increases in running VO2max and maximal treadmill time were observed in runners (mean +/- SE, 9.3 +/- 1.3%, 14.9 +/- 2.5%) and skaters (6.6 +/- 1.0%, 9.1 +/- 3.4%), but not controls. Skaters also significantly increased their skating VO2max and maximal treadmill time (8.6 +/- 1.8%, 7.9 +/- 2.9%). The magnitude of these increases was not different between the two training groups. In conclusion, in moderately active college-aged students, similar improvements in VO2max are achieved with running and in-line skating programs that are equivalent in training volume and intensity.

Use of blood lactate measurements for prediction of exercise performance and for control of training. Recommendations for long-distance running

Time over a distance, i.e. speed, is the reference for performance for all events whose rules are based on locomotion in different mechanical constraints. A certain power output has to be maintained during a distance or over time. The energy requirements and metabolic support for optimal performance are functions of the length of the race and the intensity at which it is completed. However, despite the complexity of the regulation of lactate metabolism, blood lactate measurements can be used by coaches for prediction of exercise performance. The anaerobic threshold, commonly defined as the exercise intensity, speed or fraction of maximal oxygen uptake (VO2max) at a fixed blood lactate level or at a maximal lactate steady-state (MLSS), has been accepted as a measure of the endurance. The blood lactate threshold, expressed as a fraction of the velocity associated with VO2max, depends on the relationship between velocity and oxygen uptake (VO2). The measurement of the post-competition blood lactate in short events (lasting 1 to 2 minutes) has been found to be related to the performance in events (400 to 800m in running). Blood lactate levels can be used to assist with determining training exercise intensity. However, to interpret the training effect on the blood lactate profile, the athlete's nutritional state and exercise protocol have also to be controlled. Moreover, improvement of fractional utilisation of VO2max at the MLSS has to be considered among all discriminating factors of the performance, such as the velocity associated with VO2max.

Exercise responses to running and in-line skating at self-selected paces

Exercise responses to running and in-line skating at self-selected paces. Med. Sci. Sports Exerc., Vol. 28, No. 2, pp. 247-250, 1996. The purpose of this investigation was to compare physiological responses to in-line skating and running at preferred levels of exertion. Ten males and ten females performed 15 min of in-line skating or running on two separate days. Subjects were instructed to exercise at an intensity that represented an effective cardiovascular workout. Heart rate (HR) and oxygen consumption (VO2) were monitored continuously using a portable, telemetric, open-circuit spirometry system. Subjects maintained steady rate VO2 over minutes 11-15 of in-line skating and running at speeds (mean +/- SD) of 21.7 +/- 2.4 and 12.2 +/- 2.3 km.h-1, respectively. A significantly higher (P = 0.03) VO2 (mean +/- SEM, 44.0 +/- 1.7 ml.kg-1.min-1) was observed during running compared with in-line skating (42.0 +/- 2.0 ml.kg-1.min-1), but there were no differences in ventilation, HR, or rating of perceived exertion. Consistent with the results of previous investigations, we conclude that in-line skating is an appropriate form of exercise for improving cardiorespiratory fitness. Future studies should compare the cardiovascular training effects of in-line skating and running in individuals of varying levels of fitness and skating ability.

Compromised oxygen uptake in speed skaters during treadmill in-line skating

The "sitting" posture of speed skating may result in compromised blood flow to the working muscles, thus limiting oxygen uptake. To examine this metabolic problem, male (N = 7) short track speed skaters performed running (TR), in-line skating upright (US), and in-line skating in the "sitting" position (LS) on a motor driven treadmill on randomized days. Each test consisted of four 4-min stages at 2.24, 2.68, 3.13, and 3.58 m.s-1 (5, 6, 7, and 8 mph) at 5% incline. After a brief rest, athletes performed at 4.03 m.s-1 (9 mph) with elevation increasing 1% each minute to exhaustion. Two on-ice 1000-m time trials (TT) were performed to assess the relationship between performance and laboratory measurements. Peak VO2 was lower during LS (57.2 +/- 2.7, 62.3 +/- 4.0, and 64.3 +/- 1.6; for LS, US, and TR, respectively; P < 0.05). At equivalent speeds, submaximal O2 uptake was lower for LS and blood lactate was higher (P < 0.05). LS peak VO2 (ml.kg-1.min-1) was strongly related to TT (P < 0.05). The depressed VO2 and higher blood lactate during LS may be related to decreased knee or trunk angle. Peak VO2 values during skating did not approach values during running. Evaluation of speed skaters in a sports-specific test is congruent with performance and demonstrates potential in addressing the unique physiological demands of the sport.