Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
Views
626
Download
177
 
©Journal of Sports Science and Medicine ( 2018 ) 17 , 633 - 639

Research article
Heart Rate-Index Estimates Oxygen Uptake, Energy Expenditure and Aerobic Fitness in Rugby Players
Alessandro L. Colosio1,2, Anna Pedrinolla1, Giorgio Da Lozzo1,2, Silvia Pogliaghi1,2, 
Author Information
1 Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Italy
2 Rugby Research Centre, University of Verona, Italy

Silvia Pogliaghi
✉Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Italy
Email: silvia.pogliaghi@univr.it
Publish Date
Received: 21-06-2018
Accepted: 25-09-2018
Published (online): 20-11-2018
Share this article
 
ABSTRACT

The purpose of the study was to verify the suitability of heart rate-index (HRindex) in predicting submaximal oxygen consumption (VO2), energy expenditure (EE) and maximal oxygen consumption (VO2max) during treadmill running in rugby players. Fifteen professional rugby players (99.8 ± 12.7 kg, 1.85 ± 0.09 m) performed a running incremental test while VO2 (breath-by-breath) and heart rate (HR) were measured. HRindex was calculated (actual HR/resting HR) to predict submaximal and maximal VO2 ({[(HRindex x 6)-5.0] x (3.5 body weight)}) and EE. Measured and predicted VO2 and EE were compared by two-way RM-ANOVA (method, speed), correlation and Bland-Altman analysis. Measured and predicted VO2max were compared by paired t-test, correlation and Bland-Altman analysis. Submaximal VO2 and EE significantly increased (baseline VO2: 8.1 ± 1.6 ml·kg-1·min-1 VO2max: 46.8 ± 4.3 ml·kg-1·min-1, baseline EE: 0.03 ± 0.01 kcal·kg-1·min-1, peak EE: 0.23 ± 0.03 kcal·kg-1·min-1) as a function of speed (p < 0.001 and p < 0.001 for VO2 and EE respectively) yet measured and predicted values at equal treadmill speeds were not significantly different (p = 0.17; p = 0.16) and highly correlated (r = 0.95; r = 0.94). The Bland-Altman analysis confirmed a non-significant bias between measured and estimated VO2 (measured: 40.3 ± 10.7, estimated: 40.7 ± 10.1 ml·kg-1·min-1, bias = 1.35 ml·kg-1·min-1, z = 1.12, precision = 3.39 ml·kg-1·min-1) and EE (measured: 20.0 ± 0.05 kcal·kg-1·min-1, estimated: 20.0 ± 0.05 kcal·kg-1·min-1, bias = 0.00 kcal·kg-1·min-1, z = 0.04, precision = 0.02 kcal·kg-1·min-1). Estimated and predicted VO2max were not statistically different (p = 0.91), highly correlated (r = 0.96), and showed a non-significant bias (bias = 0.17, z = 0.22, precision = 1.29 ml·kg-1·min-1). HRindex is a valid field method to track VO2, EE and VO2max during running in rugby players.

Key words: Rugby union, cardiorespiratory fitness, sports medicine, game demands


           Key Points
  • HR-index/METs relationship is valid in highly trained individuals.
  • HR-index estimates oxygen uptake and energy expenditure in rugby players during running.
  • HR-index could also allow indirect estimations of athletes’ maximal oxygen uptake at an individual or group level.
  • The main advantages of this method are: i) low costs and minimal staff training requirements ii) time efficiency iii) the possibility to obtain time-resolved EE estimates with daily frequency iv) applicability during matches/training.
  • Within the limitation of HR methods, HR-index could give insight into the energetic demands of rugby.

INTRODUCTION

Rugby Union requires players to maintain high performance levels and imposes substantial physical workloads for prolonged periods of time across the playing season (Quarrie et al., 2017). To accomplish optimum results, it is necessary to develop a range of player capacities (e.g. low to high intensity running, strength training.) and skills (e.g. passing, kicking, wrestling) in a combination that may vary according to playing position, competitive level and match situation (Austin et al., 2011). In this context, a knowledge of the demands of the game (i.e. internal and external workload and energy expenditure (EE)) it is necessary to customize training practices and nutritional strategies, for optimal body composition and performance, for specific positional roles and competitive levels (Fontana et al., 2015; 2016).

The internal and external workload of rugby has been studied using different methodological approaches like the session-rating of perceived exertion (RPE), heart rate (HR) monitors and global positioning systems (GPS) (Cunniffe et al., 2009; Halson, 2014; Quarrie et al., 2017). On the contrary, few studies have focused on EE in rugby players: overall daily EE in rugby players was estimated using SenseWear armbands (Bradley, et al. 2015a; 2015b) or calculating the EE of accelerated running by using GPS in Rugby League players (Kempton et al., 2015). However, possibly due to the practical and technical limitations of the above methods in field conditions (Morehen et al., 2016), the EE of actual playing/training in Rugby Union is still unreported.

Indirect calorimetry, based on the direct measure of oxygen uptake (VO2), is the most common method to determine EE in exercise laboratories (Jequier et al, 1987). In addition, based on the well-known linear relationship between heart rate (HR) and VO2, alternative indirect approaches for the VO2 estimate and the subsequent estimate of EE have been developed (Åstrand et al., 2003). These approaches allow accurate and precise estimates of EE in a variety of activities (Achten and Jeukendrup, 2003) and have been successfully applied in studies of elite Rugby Union (Da Lozzo and Pogliaghi, 2013); however, their practical applicability is reduced by the need of a preliminary incremental test in the laboratory (to establish the individual HR/VO2 relationship), that increases the overall financial cost and reduces the time-efficiency of the approach.

In 2011 Wicks and colleagues developed a simple HR index (HRindex) method to estimate VO2 in healthy non-athletes and clinical populations without the need for a laboratory test to determine the individual HR/VO2 relationship. The method was based on the observation that a valid linear relationship exists between HRindex (calculated as actual HR/resting HR) and VO2 expressed in multiples of the resting metabolic rate (VO2METs) (Wicks et al., 2011). Within the well-known limitations related to the use of HR measurement for VO2 estimation (Achten and Jeukendrup, 2003), the HRindex method may provide a new, low cost and easy to use alternative to existing methods to estimate VO2 and EE during Rugby activities. In fact, HR monitors are relatively “cheap” equipment, already used by elite clubs and may also represent a convenient investment for lower level clubs offering important information on the absolute and relative intensity of exercise to a wide range of coaches and athletes. Furthermore, HRindex has been investigated in its applicability in predicting aerobic fitness (VO2max) (Esco et al., 2012; Haller et al., 2013), a possibility that could be useful to determine and monitor players’ fitness levels without requiring expensive metabolic-carts.

However, this appealing field method is based on a linear HRindex/VO2 relationship that has only been validated in a non-athletic population. Consequently, the application of HRindex to individuals with a high fitness level requires preliminary validity verification.

Within this background, the current study tested the following hypotheses: i) a valid linear relationship between HRindex/VO2METs can be confirmed in rugby players; ii) VO2 and EE of incremental treadmill running can be accurately and precisely estimated based on HRindex in rugby players; iii) players’ VO2max can be estimated using HRindex.

METHODS

Subjects

Fifteen professional rugby players (24 ± 3 years, 8 forwards: 106 ± 10 kg, 1.89 ± 0.09 m, 18 ± 8 % fat mass; 7 backs: 93 ± 11 kg, 1.81 ± 0.08 m, 14 ± 6 % fat mass) playing in the Italian Rugby Union First Division, were recruited and included in the study after they gave their written, informed consent. The study was approved by the Departmental Ethics Committee and all experiments were done in accordance with the principles laid down in the Declaration of Helsinki. All participants were non-smokers, free of any musculoskeletal, respiratory, cardiovascular and metabolic conditions that may influence the physiological responses during exercise testing. All the incremental tests were conducted in the exercise physiology laboratory of the sports sciences section of the University of Verona on an electromagnetically controlled treadmill (Runrace, Technogym, Italy).

Resting heart rate and anthropometry

Participants were instructed to avoid any physical exercise in the 48 hours before the testing session. In the morning, after medical clearance and after a 10-min rest in a seated position, HR was measured for a period of 3 min, using a heart rate monitor (Polar Electro Oy, Finland, acquisition frequency: 5 seconds). Resting HR was identified as the lowest HR of the three minutes of monitoring (Haller et al., 2013). Then, body mass (digital scale, Seca 877, Seca, Leicester, UK), height (vertical stadiometer, Seca, Leicester, UK) and percentage of body fat (based on the sum of the 6-skinfold thickness (Fontana et al., 2015)) were determined.

Incremental test

On the same day, participants performed a step-wise incremental test consisting of 1-minute baseline measurements, 3 minutes of warm-up at 8.0 km/h, followed by step-wise increments of 0.5 km/h every minute until volitional exhaustion. The treadmill was set at 1% gradient to replicate outdoor over-ground running (Jones and Doust, 1996). The above ramp incremental protocol was chosen to obtain a time to exhaustion around 8-12 minutes (American College of Sports Medicine, 2017) using a method extensively described elsewhere (Pogliaghi et al., 2014). In brief, based on previous data by our group and others (Duthie et al., 2003; Pogliaghi and De Roia, 2007) we anticipated VO2max values ranging between 46 and 52 ml·kg-1·min-1; considering the following energy cost of running (American College of Sports Medicine, 2017):

we estimated a maximum running speed of 200-230 m/min (12-14 km/h). Starting from 8 km/h (i.e. the lowest speed at which all subjects would run) and using 0.5 km/h increments, subjects will be exhausted between 8-12 min.

Breath-by-breath pulmonary gas exchange and ventilation were continuously measured using a metabolic cart (Quark b2, Cosmed, Italy) as previously described (De Roia et al., 2012). Oxygen uptake (VO2), HR, and EE were calculated for each 1-minute step as average of last 10 second of each step. Maximal VO2 (VO2max) and maximal HR (HRmax) were determined as the highest values reached upon exhaustion.

Estimation of VO2 using HRindex method

After verification of Wick’s relationship between METs and HRindex (see below in “statistical analysis”), individual HRindex was calculated as actual HR/resting HR and the Wick equation was applied to estimate a 5-s average VO2 for each step during the incremental test and to estimate VO2max (Wicks et al., 2011):

Finally, energy expenditure (EE-HRindex), relative to time (kcal·min-1) was calculated for every step of the incremental exercise based on an energy equivalent for VO2 equal to 5.0 kcal·L-1 (di Prampero, 1986).

Statistical analysis

Data are presented as means ± standard deviation throughout. After preliminary assumptions were verified, the linear relationship between HRindex and METs, was modelled and Pearson’s product moment correlation coefficient was calculated. The original Wicks equation and equation derived from this sample of rugby players were compared through the difference between R2 (Field, 2013). Furthermore, differences among mean values of directly measured and estimated VO2 and between measured and estimated EE were compared by two-way Repeated Measures ANOVA (method of estimate and speed), followed by Holm-Sidak correction. In addition, directly measured and the predicted values of VO2max were compared using a paired t-test.

The correlation between measured and estimated submaximal VO2, VO2max, and between measured and estimated EE were also modelled and Pearson’s product moment correlation coefficient was calculated. Lastly, a Bland-Altman analysis followed by one-sample z test was used to determine accuracy, and precision of the measured and estimated VO2, EE, and VO2max values. All statistical analyses were performed using SigmaPlot 11.0 (Systat Software Inc) and α = 0.05; statistical significance was accepted when p < α. 95% Confidence Intervals (CI) were also reported (Cumming, 2014).

RESULTS

The mean resting value of HR was 61 ± 5 b/min. All the subjects completed the incremental test with no adverse events (time to exhaustion= 12.0 ± 2.83 minutes, maximal speed = 14 ± 1.4 km/h, VO2max = 47.1 ± 4.3 ml·kg-1·min-1). HR, VO2, and EE values increased as a function of speed during the incremental test. Submaximal and maximal data are presented in Table 1.

A strong positive and linear relationship was found between HRindex and METs (METs = 5.89 x HRindex – 4.88, R2= 0.92, Figure 1), almost identical to that reported by Wicks in sedentary individuals (METs = (HRindex x 6) – 5, R2= 0.95). The application of our equation did not significantly improve the prediction R2 compared to the original equation reported by Wicks (ΔR2 = -0.00069, p < 0.001). Therefore, the original Wicks equation was used for the estimation of VO2 and EE.

Repeated measures ANOVA showed a significant main effect of speed on the submaximal values of VO2 and EE (p < 0.001 and p < 0.001 for VO2 and EE respectively). On the contrary, there was no significant effect of method (measured vs. predicted) (p = 0.17; p = 0.16) on submaximal VO2 and EE values (Figure 2 panels A and B). Furthermore, measured and estimated values of VO2 (ml·kg-1·min-1) and measured and estimated values of EE were highly correlated (VO2: Figure 2 panel C, r = 0.96, p = 0.00, 95% CI [0.95, 0.97]; EE: Figure 2 panel D, r = 0.94, p = 0.00 95% CI [0.92, 0.95]). In addition, the Bland-Altman analysis confirmed a non-significant bias and a relatively small imprecision between measured and estimated VO2 (Figure 2 panel E, bias = 0.60 ml·kg-1·min-1, z = 0.52, precision = 2.89 ml·kg-1·min-1) and between measured and estimated EE (Figure 2 panel F, bias = 0.00 kcal·kg-1·min-1, z = 0.04, precision = 0.02 kcal·kg-1·min-1). Finally, estimated VO2max was not significantly different from the measured value (47.1 ± 4.3 vs. 46.8 ± 4.3 ml·kg-1·min-1, p = 0.91, 95% CI [44.0, 47.9]). Furthermore, measured and estimated values were highly correlated (r = 0.96) and with a non-significant bias (bias = 0.17, z = 0.22) and good precision (precision = 1.29 ml·kg-1·min-1).

DISCUSSION

With the aim to validate, in an athletic population, the use of a “field” method developed by Wicks et al. (2011) in sedentary individuals, we tested the hypothesis that VO2, EE, and VO2max can be accurately predicted using HRindex in rugby players during incremental treadmill running. The study confirmed a valid linear relationship between HRindex/VO2METs in well-trained professional rugby players, that was not different from that previously validated in non-athletic adults (Wicks et al., 2011). In agreement with our hypothesis, the predicted VO2, EE, and VO2max were not significantly different from the direct measures, and highly correlated with them. The validity of the HRindex-based approach in this population offers the opportunity to estimate submaximal VO2 and EE from simple HR measures, sparing the requirement of a preliminary test to determine the individual HR-VO2 relationship. Furthermore, HRindex could offer new and inexpensive alternatives to the existing indirect methods (e.g. 20-m shuttle run test) for the assessment and periodic monitoring of athletes’ aerobic fitness (VO2max).

The measurement of internal load and EE is particularly important in rugby, where the individualization of training and recovery strategies could be challenging as a consequence of player numbers, size and heterogeneity, the variability of movement tasks and the high training loads of the game (Fontana et al., 2015; Quarrie et al., 2013). However, the existing methods to estimate EE present limitations: the gold standard method, i.e. the doubly labelled water technique (Schoeller et al., 1986), has been used in elite Rugby League (Morehen et al., 2016) to measure EE, providing a good estimation of the EE during a certain “time window”. Still, this method is impractical to track short-term variations of EE and, when used to monitor daily or weekly EE, it is prone to error due to the confounding effect of non-rugby activities and to the possible inaccuracy in recording food consumption (Gropper and Smith, 2013). In addition, the high financial costs, the need for specific equipment and trained staff make this method inaccessible to all but the top-level elite clubs.

Match analysis and global positioning systems devices have also been used to estimate EE (Cummins et al., 2017; Kempton et al., 2015). However, these techniques may lead to possible EE underestimations due to the inability to account for static efforts (e.g. scrums, mauls) as well as short-distance running that represent the primary movement characteristics of players in the forward role during a rugby match (Buchheit et al., 2015; Dubois et al., 2017; Quarrie et al., 2013). Dubois et al. (2017) recently compared the metabolic demands of professional Rugby Union using these two methods (i.e. match analysis and GPS) and HR monitors, finding that both match analysis and GPS were unable to detect 40% of the HR-detected exertion (Dubois et al. 2017). SenseWear Armbands were also used to assess EE in Rugby Union during off-season and on-season periods (Bradley, et al. 2015a; 2015b), but their use is limited since they cannot be worn during matches, physical contact or during bad weather conditions. Finally, as for the double labelled water technique, both GPS and Armbands may be affordable/manageable by top level clubs only.

The HRindex approach allows sports scientists to estimate EE, overcoming most of the limitations of the above methods; furthermore, it eliminates the requirement of the preliminary identification of the individual HR/VO2 relationship, inherent to previously applied HR-based methods (Da Lozzo and Pogliaghi, 2013).

In the present investigation we found that the approach originally developed by Wicks et al. (2011), in non-athletic populations, retains its validity when applied to well-trained rugby players. The fact that the anthropometric (body mass, height and % body fat) and functional characteristics (VO2max) of the rugby players tested in our study were comparable to those of their international counterparts (Duthie et al., 2003a; Fontana et al., 2015). suggests the generalizability of our findings to First Division players; however, further investigation in these populations is warranted.

The use of HR to estimate and monitor EE during intermittent exercise is sometimes questioned due to: i) inability of HR to account for the anaerobic component of exercise, potentially causing an underestimation of energy expenditure of highly intense, intermittent activities; ii) a relatively slow response to changes of exercise intensity (i.e. a relatively slow “on-phase”, mirrored by a slow “off-phase” when intensity decreases, similar to the time-course of VO2) (Miyamoto and Niizeki, 1992); iii) a disproportionately high response of HR at very low exercise intensities (Achten and Jeukendrup, 2003). In addition, coaches and researchers should be aware of the effect of environmental factors and within subject variation on the HR/VO2 relationship during activity: hydration status, fatigue and increases in core temperature (Achten and Jeukendrup, 2003) may lead to non-metabolic increases of HR that could bias VO2 and EE estimation during very long training/game sessions and in the summer period.

Within these limitations, HR has been shown to be a valuable method to the track physiological responses in field conditions during different activities ranging from soccer (Alexandre et al., 2012) to a military loaded run (Colosio and Pogliaghi, 2018); furthermore, no differences were found between HR response during field or laboratory tests performed by either professional or amateur soccer players (Chamari et al., 2005; Hoff et al., 2002). These findings support the overall validity of HR monitoring to estimate VO2 and EE during outdoor activities/team sports under ecological conditions.

The third objective of this investigation was to compare directly measured values of VO2max with the values predicted using HRindex. Similar to previous studies (Esco et al., 2012; Haller et al., 2013; Wicks and Oldridge, 2016), the average predicted VO2max (47.1 ± 4.3 ml·kg-1·min-1) was not significantly different from the measured VO2max (46.8 ± 4.3 ml·kg-1·min-1, p = 0.91) and they were highly correlated (r = 0.96). This finding supports the general applicability of HRindex to investigate the mean fitness level of a group of subjects (or team). Furthermore, and in contrast with the existing literature, (Esco et al., 2012; Haller et al., 2013), our study demonstrated a good agreement between the predicted and measured values of VO2max (mean bias between values = 0.17 ml·kg-1·min-1, z = 0.22, precision = 1.29 ml·kg-1·min-1). While these results seem promising, repeatability of the method remains to be determined.

It should be noticed that the ramp incremental protocol used in this investigation was chosen to respond to two main requirements: i) the validation of the HRindex/VO2 relationship across a wide range of intensities (from low to maximal effort) without including some of the confounding factors that could be present in the most common field tests (e.g. changes of direction, terrain characteristics) ii) to obtain a time to exhaustion around 8-12 minutes and by doing so, an accurate VO2max (American College of Sports Medicine, 2017). Regarding the second point, our time to exhaustion was slightly higher than expected (12.0 ± 2.83 minutes). However, it has been shown that, VO2max is unaffected by speed increments in trained subjects (Kang et al. 2001; Sperlich et al. 2015). The above data support the validity of the measured values for VO2max of the present study.

Finally, considering the laboratory environment of this investigation and the limitations of HR measurements, further studies should investigate HRindex applicability outside the laboratory environment, during training/game and field testing sessions.

CONCLUSION

We validated the use of the HRindex, originally developed by Wicks et al. (2011) on a non-athletic population, to estimate VO2, EE and VO2max of treadmill running in professional rugby players. The main advantages of HRindex in comparison to existing methods are: i) low costs and minimal staff training requirements ii) time efficiency iii) the possibility to obtain time-resolved EE estimates with daily frequency iv) the applicability during matches/training. Finally, HRindex appears to provide accurate estimates of VO2max in this population of professional rugby players. Within the limitation of HR-based methods, and even if further studies are needed to validate EE estimates deriving from HRindex in ecological conditions, this low cost and easy-to-use field method could give insight into the demands of the game in different positional roles and competitive levels, informing the customization of training practices and nutritional strategies.

ACKNOWLEDGEMENTS

The authors express their gratitude to the participants who made this data collection possible. The reported experiments comply with the current laws of the country; in which they were performed. The authors have no conflicts of interests to declare.

AUTHOR BIOGRAPHY

Journal of Sports Science and Medicine Alessandro L. Colosio
Employment: PhD Student at University of Verona, Strength and Conditioning Coach of the Rugby Research Centre, University of Verona.
Degree: MSc
Research interests: Exercise Physiology with particular interest in oxygen uptake kinetics, Sports performance.
E-mail: alessandro.colosio@univr.it
 

Journal of Sports Science and Medicine Anna Pedrinolla
Employment: Post Doc Fellow at University of Verona.
Degree: PhD
Research interests: Exercise Physiology and vascular function.
E-mail: anna.pedrinolla@univr.it
 

Journal of Sports Science and Medicine Giorgio Da Lozzo
Employment: Strength and Conditioning Coach at Benetton Treviso Rugby, adjunct Professor at the Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona. Head of the Rugby Research Centre, University of Verona.
Degree: PhD
Research interests: Sports performance, injury prevention, workload management, elite rugby players.
E-mail: giorgio.dalozzo@univr.it
 

Journal of Sports Science and Medicine Silvia Pogliaghi
Employment: Assistant Professor at the Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona. Head of the Rugby Research Centre, University of Verona.
Degree: MD, PhD
Research interests: Exercise Physiology with particular interest to the mechanisms that regulate acute and adaptive responses to exercise in physiological and pathological conditions, sports performance.
E-mail: silvia.pogliaghi@univr.it
 
 
REFERENCES
Journal of Sports Science and Medicine Achten J., Jeukendrup A.E. (2003) Heart rate monitoring: applications and limitations. Sports Medicine 33, 517-538.
Journal of Sports Science and Medicine Alexandre D., Da Silva C.D., Hill-Haas S., Wong D.P., Natali A.J., De Lima J.R.P., Filho M.G.B.B., Marins J.J.C.B., Garcia E.S., Karim C. (2012) Heart ratemonitoring in soccer: Interest and limits during competitive match play and training, practical application. Journal of Strength and Conditioning Research 26, 2890-2906.
Journal of Sports Science and Medicine Austin D., Gabbett T., Jenkins D. (2011) The physical demands of Super 14 rugby union. Journal of Science and Medicine in Sport 14, 259-263.
Journal of Sports Science and Medicine Åstrand P.O., Rodahl K., Hans A.D., Stromme B.S. (2003) Textbook of work physiology : physiological bases of exercise. Human Kinetics.
Journal of Sports Science and Medicine Bradley W.J., Cavanagh B., Douglas W., Donovan T.F., Twist C., Morton J.P., Close G.L. (2015a) Energy intake and expenditure assessed ‘in-season’ in an elite European rugby union squad. European Journal of Sport Science 15, 469-479.
Journal of Sports Science and Medicine Bradley W.J., Cavanagh B.P., Douglas W., Donovan T.F., Morton J.P., Close G.L. (2015b) Quantification of training load, energy intake, and physiological adaptations during a rugby preseason: a case study from an elite European rugby union squad. Journal of Strength and Conditioning Research 29, 534-544.
Journal of Sports Science and Medicine Buchheit M., Manouvrier C., Cassirame J., Morin J.B. (2015) Monitoring locomotor load in soccer: Is metabolic power, powerful?. International Journal of Sports Medicine 36, 1149-1155.
Journal of Sports Science and Medicine Chamari K., Hachana Y., Kaouech F., Jeddi R., Moussa-Chamari I., Wislff U. (2005) Endurance training and testing with the ball in young elite soccer players. British Journal of Sports Medicine 39, 24-28.
Journal of Sports Science and Medicine Colosio A.L., Pogliaghi S. (2018) Quantification of energy expenditure of military loaded runs: what is the performance of laboratory-based equations when applied to the field environment?. Journal of the Royal Army Medical Corps 164, 253-258.
Journal of Sports Science and Medicine Cumming G. (2014) The New Statistics: Why and How. Psychological Science 25, 7-29.
Journal of Sports Science and Medicine Cummins, C., Gray, A., Shorter, K., Halaki, M. and Orr, R. (2017) Energetic demands of interchange and full-match rugby league players. Journal of Strength and Conditioning Research Jan 20. Epub ahead of print.
Journal of Sports Science and Medicine Cunniffe B., Proctor W., Baker J.S., Davies B. (2009) An Evaluation of the Physiological Demands of Elite Rugby Union using Global Positioning System Tracking Software. Journal of strength and conditioning research / National Strength & Conditioning Association 23, 1195-1203.
Journal of Sports Science and Medicine De Roia G., Pogliaghi S., Adami A., Papadopoulou C., Capelli C. (2012) Effects of priming exercise on the speed of adjustment of muscle oxidative metabolism at the onset of moderate-intensity step transitions in older adults. American journal of physiology. Regulatory, Integrative and comparative physiology 302, 1158-1166.
Journal of Sports Science and Medicine di Prampero P.E. (1986) The energy cost of human locomotion on land and in water. International Journal of Sports Medicine 7, 55-72.
Journal of Sports Science and Medicine Dubois R., Paillard T., Lyons M., McGrath D., Maurelli O., Prioux J. (2017) Running and metabolic demands of elite rugby union assessed using traditional, metabolic power, and heart rate monitoring methods. Journal of Sports Science and Medicine 16, 84-92.
Journal of Sports Science and Medicine Duthie G., Pyne D., Hooper S. (2003) Applied physiology and game analysis of rugby union.. Sports medicine (Auckland, N.Z.) 33, 973-991.
Journal of Sports Science and Medicine Esco M.R., Olson M.S., Williford H.N., Mugu E.M., Bloomquist B.E., McHugh A.N. (2012) Crossvalidation of two heart rate-based equations for predicting VO2max in white and black men. Journal of Strength and Conditioning Research / National Strength & Conditioning Association 26, 1920-1927.
Journal of Sports Science and Medicine Field A. (2013) Discovering Statistics using IBM SPSS Statistics. Discovering Statistics using IBM SPSS Statistics , 297-321.
Journal of Sports Science and Medicine Fontana F.Y., Colosio A., De Roia G.F., Da Lozzo G., Pogliaghi S. (2015) Anthropometrics of Italian senior male rugby union players: From elite to second division. International Journal of Sports Physiology and Performance 10, 674-680.
Journal of Sports Science and Medicine Fontana F.Y., Colosio A.L., Da Lozzo G., Pogliaghi S. (2016) Player’s success prediction in rugby union: From youth performance to senior level placing. Journal of Science and Medicine in Sport 20, 409-414.
Journal of Sports Science and Medicine Gropper, S. and Smith, J. (2013) Advanced nutrition and human metabolism. Biochemical Education 20.
Journal of Sports Science and Medicine Haller, J.M., Fehling, P.C., Barr, D.A., Storer, T.W., Cooper, C.B. and Smith, D.L. (2013) Use of the hr index to predict maximal oxygen uptake during different exercise protocols. Physiological Reports 1(5).
Journal of Sports Science and Medicine Halson S.L. (2014) Monitoring Training Load to Understand Fatigue in Athletes. Sports Medicine 44, 139-147.
Journal of Sports Science and Medicine Health W.K.W., Health W., American College of Sports Medicine (2017) ACSM’S Guidelines for Exercise Testing and Prescription. Lippincott Williams & Wilkins.
Journal of Sports Science and Medicine Hoff J., Wisløff U., Engen L.C., Kemi O.J., Helgerud J. (2002) Soccer specific aerobic endurance training. British Journal of Sports Medicine 36, 218-221.
Journal of Sports Science and Medicine Jequier E., Acheson K.J., Schutz Y. (1987) Assessment of energy expenditure and guel utilization in man. Annual review of Nutrition 7, 187-208.
Journal of Sports Science and Medicine Jones A.M., Doust J.H. (1996) A 1% treadmill grade most accurately reflects the energetic cost of outdoor running. Journal of Sports Sciences 14, 321-327.
Journal of Sports Science and Medicine Kang J., Chaloupka E.C., Mastrangelo M.A., Biren G.B., Robertson R.J. (2001) Physiological comparisons among three maximal treadmill exercise protocols in trained and untrained individuals. European Journal of Applied Physiology 84, 291-295.
Journal of Sports Science and Medicine Kempton T., Sirotic A.C., Rampinini E., Coutts A.J. (2015) Metabolic power demands of rugby league match play. International Journal of Sports Physiology and Performance 10, 23-28.
Journal of Sports Science and Medicine Miyamoto Y., Niizeki Y. (1992) Dynamics of ventilation, circulation, and gas exchange to incremental and decremental ramp exercise. Journal of applied physiology (Bethesda, Md. : 1985) 72, 2244-2254.
Journal of Sports Science and Medicine Morehen J.C., Bradley W.J., Clarke J., Twist C., Hambly C., Speakman J.R., Morton J.P., Close G.L. (2016) The assessment of total energy expenditure during a 14-day in-season period of professional rugby league players using the doubly labelled water method. International Journal of Sport Nutrition and Exercise Metabolism 26, 464-472.
Journal of Sports Science and Medicine Pogliaghi S., Bellotti C., Paterson D.H. (2014) Tailored ‘ Submaximal Step Test for VOmax Prediction in Healthy Older Adults. Journal of Aging and Physical Activity 22, 261-268.
Journal of Sports Science and Medicine Quarrie K.L., Hopkins W.G., Anthony M.J., Gill N.D. (2013) Positional demands of international rugby union: Evaluation of player actions and movements. Journal of Science and Medicine in Sport 16, 353-359.
Journal of Sports Science and Medicine Quarrie K.L., Raftery M., Blackie J., Cook C.J., Fuller C.W., Gabbett T.J., Gray A.J., Gill N., Hennessy L., Kemp S., Lambert M., Nichol R., Mellalieu S.D., Piscione J., Stadelmann J., Tucker R. (2017) Managing player load in professional rugby union: a review of current knowledge and practices. British Journal of Sports Medicine 51, 421-427.
Journal of Sports Science and Medicine Schoeller D.A., Ravussin E., Schutz Y., Acheson K.J., Baertschi P., Jequier E., Jéquier E. (1986) Energy expenditure by doubly labeled water: validation in humans and proposed calculation. American Journal of Physiology - Regulatory, Integrative and Comparative Physiology 250, 823-830.
Journal of Sports Science and Medicine Sperlich P.F., Holmberg H.C., Reed J.L., Zinner C., Mester J., Sperlich B. (2015) Individual versus standardized running protocols in the determination of VOmax.. Journal of Sports Science and Medicine 14, 386-393.
Journal of Sports Science and Medicine Wicks J.R., Oldridge N.B., Nielsen L.K., Vickers C.E. (2011) HR index-a simple method for the prediction of oxygen uptake. Medicine and Science in Sports and Exercise 43, 2005-2012.
Journal of Sports Science and Medicine Wicks, J.R. and Oldridge, N.B. (2016) How accurate is the prediction of maximal oxygen uptake with treadmill testing. PLoS ONE, 11(11).
 
 
 
Home Issues About Authors
Contact Current Editorial board Authors instructions
Email alerts In Press Mission For Reviewers
Archive Scope
Supplements Statistics
Most Read Articles
  Most Cited Articles
 
    
 
JSSM | Copyright 2001-2018 | All rights reserved. | LEGAL NOTICES | Publisher

It is forbidden the total or partial reproduction of this web site and the published materials, the treatment of its database, any kind of transition and for any means, either electronic, mechanic or other methods, without the previous written permission of the JSSM.

This work is licensed under a Creative Commons License Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.