Evaluation of dry-land ergometry in assessment of cardiopulmonary and metabolic responses to arm and leg exercise in swimmers
Dry-land ergometry has been proposed as an alternative method to water-based testing in an attempt to circumvent the difficulties associated with physiological assessment of swimmers during swimming itself. The aim of the studies presented in this thesis was to evaluate the usefulness of dry-land ergometry. The objectives of the studies presented in this thesis were to ascertain whether dry-land measurements could differentiate between trained and untrained swimmers, assess the effects of training and reflect water-based measurements. To realise this aim and the objectives, three studies that assessed physiological parameters of swimmers using dry-land ergometry and water-based testing were undertaken. The first study compared lactate and oxygen uptake responses to separate dry-land armpulling and leg-kicking in recreational (RSW) and collegiate swimmers (SW). The exercise intensity at a blood lactate concentration of 4 mmol-l" (E~) and the peak oxygen uptake (V OZpeok), peak exercise intensity (ElpeU.)and peak lactate (HLapeU.)responses to incremental arm-pulling and leg-kicking were established for both groups. The results showed that, for armpulling, SW achieved higher E~ (94 ± 6.0 W versus 70 ± 6.3 W; P<0.05) and EIpeok(114 ± 6.0 W versus 90 ± 4.0 W; P<0.05) than RSW, whereas, for leg-kicking, none of the responses differed between the two groups. These results suggested that arm conditioning was enhanced in SW and this was reflected in the dry-land measurements of E4nM and EIpeok. Therefore, it was possible to establish the differences in physiological responses between SW and RSW using dryland ergometry. The second study assessed the effects of arms- versus legs-only swimming training on performance indices and gas exchange responses to separate dry-land arm-pulling and leg-kicking in competitive swimmers. Two groups of swimmers performed arms- (ARMS) or legs-only (LEGS) swimming exercises for 20% of their training time, 3 times a week for six weeks. Waterbased (swim trials) and dry-land assessments were conducted prior to and immediately after the 6-week training period. The swim trials included a 200 m arms-only (200ARMS),a 200 m legs-only (200u,GS) and a 400 m (400ruu) front crawl test. Distance per pull (DPP) and distance per kick (DPK) for 200ARMSand 200LEOS were calculated from video recordings. The dry-land assessments included measurements of oxygen uptake (V02), ventilatory threshold (VT) and total exercise time (TEn during an incremental arm-pulling and leg-kicking exercise test. The results showed that arm training improved 200ARMS(184 ± 10.0 s versus 164 ± 6.0 s) and DPP (+10 ± 3%) in the ARMS and leg training improved 200u,os (223 ± 10.0 versus 211 ± 10.0 s) and DPK (+5 ± 2%) in the LEGS (all at P<0.05). The changes due to arm training were reflected in the armII ulling measurements of increased VTw (+20 ± 3%), reduced V02 at 60W (-18 ± 2%) and increased TET (465 ± 8 s versus 675 ± 15 s), whereas the changes due to leg training were reflected in VT w (+37 ± 5%) and reduced V02 at 60W (-20 ± 3%). These results suggested that arms- or legs-only swimming training induces changes in arms- or legs-only swmunmg performance, but these do not necessarily translate into improved full-stroke swimming performance. Also, results indicate that dry-land ergometry can detect the changes due to armsor legs-only swimming training in the physiological responses to arm-pulling or leg-kicking. The third study compared the cardiopulmonary responses to whole-body, arms- and legsonly dry-land exercise and free swimming. The peak oxygen uptake (V 02pea) and peak heart rate (HR,eu) responses to whole-body, arm-pulling and leg-kicking exercise were established in both exercise modalities. The results showed that V02peak was higher in whole-body exercise than arms-only or legs-only exercise in both exercise modalities (dry-land: 3.69 ± 0.18 l-min" versus 3.18 ± 0.43 lmin" and 3.15 ± 0.54 l-min", respectively. P<0.05, swimming: 4.12 ± 0.84 l-min" versus 3.36 ± 0.52 l-min" and 3.55 ± 0.43 l-min", respectively; P<0.05) and also that whole-body V02peak was 10% higher during free swimming than during dry-land exercise. No differences were noted for HRpea between whole-body, arms-only and legs-only exercise in both exercise modalities. These results suggested that the higher VOZpeak noted for whole-body free swimming compared to combined arm-leg exercise could be due to limitations in the design of the dry-land ergometer used as the difference was small. Therefore, it was shown that dry-land measurements compare favourably with water-based measurements. The use of dry-land ergometry presents several limitations, which are mainly concerned with the design of this equipment. However, all the above fmdings demonstrate that dry-land ergometry might be a valuable tool for assessment of those physiological responses (i.e. continuous measurement of gas exchange measures) that, at present, are difficult to be conducted in the water. Therefore, dry-land ergometry might be used as an alternative and/or supplement to water-based testing.