A comparison of physiological responses to rowing on friction-loaded ...

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were investigated on Gjessing, Rowperfect fixed-mechanism and Rowperfect free-mechanism rowing ergo- meters. Heart rate, oxygen uptake (VÇO2), ...

Jour nal of Sports Sciences, 1999 , 17, 143± 149

A comparison of physiological responses to rowing on friction-loaded and air-braked ergometers 1

2

N. M AHON Y, * B. D ON NE and M . O ’ BRIEN 1

1

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Department of Anatomy and D epartm ent of Physiology, Tr inity C ollege D ublin, D ublin 2, Ireland

Accepted 15 February 1998

The physiological responses of 10 trained rowers to a progressive incremental rowing protocol to exhaustion were investigated on G jessing, Rowperfect W xed-mechanism and Rowperfect free-mechanism rowing ergom eters. Heart rate, oxygen uptake ( VÇ O 2 ), ventilation (VÇ E) and blood lactate were determined at m atched power values for each ergometer. The mean power and heart rate at the lactate anaerobic threshold were determined by graphical interpolation of data for each ergom eter. Analysis of variance and linear regression showed diV ering responses at matched power and an approxim ate 40± 50 W diV erence in power at the lactate anaerobic threshold when comparing the friction-loaded Gjessing with the air-braked Rowperfect W xed and Rowperfect free ergom eters (P < 0.01). No signiW cant diV erences were noted when comparing the air-braked Rowperfect W xed and Rowperfect free ergom eters. However, com parisons of VÇ O 2 , VÇ E and blood lactate at given heart rates and of heart rate at the lactate anaerobic threshold showed no signiW cant di V erences between ergometers. Our results indicate similar physiological pro W les for all ergom eters tested when com pared at equivalent heart rates, but diV erences when com pared at m atched power. A direct comparison of the data from Gjessing (friction-loaded) with Rowperfect W xed and Rowperfect free (air-braked) ergometers would therefore require a correction factor for inter-ergometer variation in displayed power data. K eyw ords : heart rate, lactate, oxygen uptake, rowing ergom etry, ventilation.

Introduction Rowing ergom eters were developed in an attem pt to reproduce m ovem ent and resistance of on-water rowing. T hey are w idely used to describe the physiological proW les of rowers. Resistance to row ing on-water is sim ulated on m ost ergom eters by rotation of a X ywheel loaded either by friction of a weighted belt or by air resistance created by rotating vanes. Popular versions of these two types of ergom eter are the Gjessing (A.S. H aby, N orway) and the Concept II (M orrisville, VT, U SA) respectively. Com petitive rowers often train using ergom eters. Both physiological and biom echanical advances in ergom eter design, which result in greater sport speciW city, are im portant for rowers when training and for exercise physiologists involved in research and testing. The physiological responses of elite rowers have been docum ented longitudinally by Hagerm an (1984), Secher (1983, 1993) and Steinacker (1993). * Author to w hom all correspondence should be addressed. 0264 ± 0414/99

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1999 E & FN Spon

Ergom eter assessm ent has allowed group and individual training program m es to be m onitored and optim ized (K ram er et al., 1994). T he eV ect of variations in test protocol and ergom eter design have been studied during 6-m in all-out and progressive increm ental test protocols (M ahler et al., 1984; U rhausen et al., 1987) and in com parisons of friction-loaded G jessing versus air-braked Concept II ergom eters (Hahn et al., 1988; Lorm es et al., 1993). O ptim ization of physiological responses to rowing ergom etr y has been studied using increm ental loading (Jensen and Katch, 1991). Biom echanical studies have investigated skill factors by analysing force± tim e proW les of the row ing stroke and kinem atic body segm ent analysis (M artindale and Robertson, 1984; Roth et al., 1993). T he reproduction of eY cient rowing patterns, stroke-to-stroke consistency and greater m ean propulsive power per unit body m ass have been reported to be accurate predictors of on-water perform ance (Sm ith and Spinks, 1995). The row ing ergom eters used in these studies are extrem ely useful tools for the investigation of rowing physiology. However, rowers

144 themselves have criticized the subjective `feel’ of W xed friction-loaded and air-braked m echanism s. D uring the recovery phase of on-water rowing, the m ass of the boat slides underneath the rower (the rower allow s the foot stretcher to m ove towards him ). T he opposite occurs during ergom eter row ing; with the loading m echanism and slide bar W xed, the m ass of the rower m ust m ove up and dow n the slide bar during the recovery and propulsive phases of the rowing stroke. T he Row perfect is a new ergom eter w hich has a freely m oving air-braked system . T his m echanical variation incorporates extra elem ents of skill and feel to control m ovem ent of the free m echanism during the recover y phase of the rowing action. W hether this new biom echanical sim ulation of the rowing action results in any changes in physiological eY ciency com pared with the older W xed-m echanism devices is unknow n. In this study, we investigated the physiological responses of rowers to a progressive increm ental test protocol using three ergom eters. Variation in the loading m echanism was exam ined by com paring the friction-loaded Gjessing w ith the air-braked Rowperfect with a Wxed m echanism . T he eV ect of the recent innovation in ergom eter design ± the Rowperfect freeXoating m echanism ± was investigated by com paring Rowperfect ergom eters w ith a W xed and free m echanism respectively.

M aterials and m ethods Ten rowers, all of whom were m em bers of a national lightweight team , provided w ritten inform ed consent to participate in the study. T heir m ean ( ± s) physical characteristics were as follows: age 24.0 ± 3.5 years, height 183 ± 3 cm, body m ass 76 ± 3 kg, body fat 10 ± 2% . All rowers had international row ing or sculling experience; nine of the rowers had rowed or sculled for m ore than 10 years and the youngest rower had sculled for 5 years. In addition to a m edical questionnaire and physical exam ination, the follow ing investigations were perform ed before testing to rule out asthm a, anaem ia and subclinical infection: spirom etry, blood haem aglobin concentration, haem atocrit and white cell count. To avoid glycogen depletion and dehydration, the rowers were given nutritional advice and were required to under take light training only on the days before testing. T he rowers com pleted the following row ing test schedule over 6± 8 days: (1) G jessing, (2) Rowperfect Wxed-m echanism and (3) Rowperfect free-m echanism . This non-random order of testing allowed fam iliarization on the Row perfect free-m echanism ergom eter during recover y after com pletion of tests 1 and 2. After recording data at rest, the par ticipants rowed for 3 m in

M ahony et al. at each power output with a 1-m in blood sam pling interval between increm ents. Power was m easured by ergom eter power display units. The initial power was 160 W, with increm ents of 40 W until exhaustion. H eart rate was m easured by short-range radio telem etr y (Polar Electro, Kem pele, Finland). Expired air was collected using a H ans Rudolph face m ask connected by a hose system to a M ihnjardt O xycon 4 gas analyser (Odijk, T he N etherlands). O xygen uptake and ventilation values were displayed at 30-s intervals. Blood lactate was m easured using a YSI 1500 Sport analyser (Yellow Springs Instrum ents, Yellow Springs, OH , U SA). Blood sam ples were taken from the earlobe using heparinized capillary tubes and transferred to the analyser by m icropipette. The Rowperfect ergom eter (C AR E, T he N etherlands) has a conventional sliding seat and air-braked X ywheel. The foot stretcher and X ywheel are incorporated into a free-X oating m echanism w hich m oves up and dow n the single, centrally placed slide bar. A self-recoiling chain with attached oar handle drives the X ywheel. The inner cog setting for the chain and a 31-cm plastic disc attached to the side of the X ywheel housing (for increasing or decreasing the cavitation eV ect) were used as the constant resistance settings for both the Rowperfect W xed and Rowperfect free ergom eters. O n the unm odiW ed Rowperfect free ergom eter, the sliding seat rem ained alm ost static (m ovem ent 0.9), and when m atched for equivalent heart rate, VÇ O 2 was sim ilar for all ergom eters. Scatter plots of VÇ O 2 versus heart rate also show convergence of the data points across all ergom eter types, sim ilar to that for blood lactate concentration versus heart rate.

F igu re 3 The relationship between lactate concentration and heart rate for the Gjessing (s ), Rowperfect W xed (h ) and Rowperfect free (n ) ergometers. The blood lactate concentration was sim ilar during incremental rowing on all ergom eters when compared at given heart rates (error bars represent the standard error of the mean).

148 T he stroke rate response to increasing power and at a given heart rate was exam ined. In response to increasing power, there were no signiW cant diV erences in stroke rate across the three ergom eters at 160 and 200 W. However, at 240 W, highly signiW cant diV erences were noted between the G jessing and Row perfect W xed ergom eters (P < 0.01). W ith further increases in power to 280, 320 and 360 W, there were signiW cant differences in stroke rate between the G jessing and both Rowperfect ergom eters (P < 0.01). A com parison of stroke rate for the air-braked ergom eters showed no signiW cant diV erences. To provide stroke rate data at equivalent heart rates, third-order polynom ial curves were plotted (r 2 ³ 0.98 for all data plots). Stroke rates at hear t rates of 130± 170 beats ´ m in - 1 were calculated and com pared for all three ergom eters. All stroke rates at m atched heart rates were sim ilar, except for the Gjessing versus Row perfect W xed ergom eter at a heart rate of 170 beats ´ m in - 1 . Essentially, there was no apparent difference in stroke rate between the ergom eters at £ 200 W or at any subm axim al heart rate (< 170 beats ´ m in - 1 ).

D iscussion In this study, we found signiW cant diV erences between the G jessing ergom eter and the Row perfect W xed and Rowperfect free ergom eters w hen power was calculated and read from individual ergom eter display units. Physiological param eters (heart rate, VÇ O 2 and blood lactate concentration) com pared at m atched powers showed signiW cant diV erences between the m echanically braked G jessing and the air-braked Rowperfect W xed and Rowperfect free ergom eters. Com parisons of VÇ O 2 and blood lactate concentration at a given heart rate revealed no signiW cant diV erences between the ergom eters. W hen com paring the other physiological variables with heart rate, we assum ed negligible or no training eV ect in the heart rate response over the short tim efram e of the study. T he experim ental design was such that confounding variables of diurnal variation in perform ance, dehydration and glycogen depletion were kept to a m inim um . We conclude, therefore, that there were no physiological diV erences during increm ental row ing on the G jessing, Rowperfect W xed and Rowperfect free ergom eters and that a discrepancy of approxim ately 40± 50 W exists in power derivation between the Gjessing and Rowperfect ergom eter display units. Lorm es et al. (1993) suggested a higher anaerobic eV ort on the friction-loaded G jessing com pared with the air-braked C oncept II; the results of our study do not support this view. Lorm es et al. used a slightly diV erent progressive increm ental test protocol (initial power of 100 W increasing by 50 W ever y 3 m in until

M ahony et al. exhaustion with a 30-s blood sam pling interval). T hey found sim ilar m axim um values for blood lactate concentration and heart rate on the G jessing and C oncept II, but found blood lactate concentration to be lower on the Concept II than on the G jessing at any given heart rate. In this study, there m ay have been biom echanical diV erences in the force± velocity proW les of the row ing stroke on each ergom eter; however, the heart rate± blood lactate concentration relationship across ergom eter types was sim ilar. H ahn et al. (1988) and Lorm es et al. (1993) cited energy losses in the transm ission system ± the return of the G jessing sliding pole during the recover y phase of the rowing stoke ± as one explanation for the diV erence in power between ergom eters. T he power discrepancy of 40± 50 W was caused either by greater frictional losses in the m ore com plex gearing system on the G jessing or by the Row perfect display unit overestim ating power. T he Row perfect display, however, has been veriW ed by m easurem ents of force and displacem ent on the oar handle to within ± 1% (U. G rossler et al., unpublished data). W hen com paring the air-braked ergom eters (Rowperfect Wxed vs Rowperfect free), for w hich power was derived from the sam e display unit, no diV erences in physiological response were noted. A greater physiological cost m ight be expected on the W xed ergom eter, as the greater body m ass of the rower ( » 75 kg) has to m ove up and down the slide bar com pared with the m ovem ent of the lighter m ass of the m echanism ( » 17.5 kg) on the free-X oating ergom eter (Rowperfect free). A com parison of `no-load’ rowing on the Rowperfect Wxed and Rowperfect free ergom eters has show n differences in heart rate of 10 beats ´ m in - 1 at any given stroke rate (C. Rekers, unpublished data); in the present study, however, with loaded rowing on both types of ergom eter, no diV erence was found. Statistical analysis of blood lactate concentration (2 m m ol ´ l- 1 , 4 m m ol ´ l- 1, heart rate at the lactate anaerobic threshold) and VÇ O 2 versus heart rate showed no signiW cant diV erences across all three ergom eters. Analysis of the stroke rate data provides sim ilar W ndings to the com parison of physiological data versus power and heart rate; that is, signiW cant diV erences in stroke rate versus power but essentially sim ilar data for stroke rate versus heart rate (w ith only one exception in the com parison of the Rowperfect Wxed and G jessing ergom eters at near m axim al eV ort). The stroke rates at subm axim al heart rates ( £ 170 beats ´ m in - 1 ) were essentially the sam e; at higher heart rates, however, individual variation between rowers becam e apparent. In conclusion, we found no diV erences in physiological variables between the G jessing, Rowperfect Wxed and Row perfect free ergom eters. O ur results

Physiological responses to rowing ergometr y support the use of the Rowperfect ergom eter as a viable alternative for the physiological testing of rowers, m any of w hom believe the `feel’ of rowing on the Row perfect free is better than on both the G jessing and Row perfect W xed ergom eters.

R eferences Hagerman, F.C. (1984). Applied physiology of rowing. Sports M edicine , 1 , 303± 326. Hahn, A., Tumilty, D. and Telford, R. (1988). Physiological testing of oarswomen on Gjessing and Concept II rowing ergometers. Excel , 5 , 19± 22. Jensen, R.L. and Katch, F.I. (1991). A new approach to rowing ergometry: Establishing exercise intensity relative to maximum force output. European Jour nal of Applied Physiolog y , 62 , 44± 48. Kram er, J., Leger, A., Paterson, D. and M orrow, A. (1994). Rowing performance and selected descriptive W eld and laboratory variables. C anadian Jour nal of A pplied Physiology , 19 , 174± 184. Lorm es, W., Buckwitz, R., Rehbein, H. and Steinacker, J.M . (1993). Perform ance and blood lactate on Gjessing and Concept II rowing ergometers. Inter nation al Jour nal of Sports M edicine , 14 (suppl. 1), S29± S31.

149 M ahler, D., Andrea, B. and Andresen, D.C. (1984). C omparison of 6 m inute `all out’ and incremental exercise tests in elite oarsm en. M edicine and Science in Sports and E xercise , 16 , 567± 571. M artindale, W.O. and Robertson, D.G.E. (1984). M echanical energy in sculling and in rowing an ergometer. C anadian Jour na l of Applied Sport Sciences , 9 , 153± 163. Roth, W., Schwanitz, P., Bas, P. and Bauer, P. (1993). Force± time characteristics of the rowing stroke and corresponding physiological m uscle adaptions. Inter nation al Jour nal of Sports M edicine , 14 (suppl. 1), S32± S34. Secher, N.H. (1983). The physiology of rowing. Jour nal of Sports Sciences , 1 , 23± 53. Secher, N.H. (1993). Physiological and biom echanical aspects of rowing: Implications for training. Sports M edicin e , 15 , 24± 42. Sm ith, R.M. and Spinks, W.L. (1995). Discrim inant analysis of biom echanical diV erences between novice, good and elite rowers. Jour nal of Sports Sciences , 13 , 377± 385. Steinacker, J. (1993). Physiological aspects of training in rowing. Inter nationa l Jour nal of Sports M edicin e , 14 (suppl. 1), 3± 10. Urhausen, A., Weiler, B. and Kinderman, W. (1987). Behaviour of lactate and catecholam ines in di V erent rowing ergom etric test procedures. D eutsche Zeitschr ift f  r Sportm edizin , 38 , 11± 19.

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