Pulmonary oxygen uptake kinetics in middle-and long-distance runners.

The overall aim of this thesis was to evaluate the importance of pulmonary oxygen uptake (VO[2]) kinetics, in the moderate-domain, in the assessment of endurance-trained runners. Accordingly, there were five objectives: 1) to quantify the reproducibility of measures of VO[2] kinetics; 2) to characterise and compare VO[2] kinetics during the on-and off-transients in middle-distance (MD) and long-distance (LD) runners; 3) to assess the relationship between VO[2] kinetics and maximal VO[2] (VO[2Max]), ventilatory threshold (V[T]) and running economy (RE); 4) to determine the relationship between VO[2] kinetics and running performance and 5) to assess whether VO[2] kinetics is a determinant of running performance.Twelve participants performed two assessments of VO[2] kinetics on separate days to determine the reproducibility. Paired t-tests showed that parameters from test 1 and test 2 did not differ (P >0.05). Furthermore, narrow 95% limits of agreement (LOA), low measurement and method error suggested that the on- and off-transient time-constants (pion and pioff), mean response times (MRT[on] and MRT[off]) and amplitudes (A[on] and A[off]) were reproducible and could be used for the assessment of runners. Subsequently, VO[2] kinetics were compared in 10 MD and 10 LD runners. There was a tendency for pion (12.5 +/- 2.3 s vs. 14.2 +/- 3.1 s, P = 0.178) and pioff (24.1 +/- 2.3 s vs. 27.1 +/- 3.0 s, P = 0.023) to be shorter in LD than MD runners respectively, despite similar VO[2Max] (MD = 60.0 +/- 4.9 ml-kg[-1]min[-1]; LD = 59.0 +/- 6.3 ml-kg[-1]-min[-1], P = 0.689). Differences in VO[2] kinetics between MD and LD runners were attributed to approaches to training since the volume of training was greater in LD (64.0 +/- 15.7 km-wk[-1]) than MD (47.5 +/- 15.7 km-wk[-1]) runners (P = 0.047). To detail the relationships between VO[2] kinetics and other measures of aerobic function (VO[2max], V[t] and RE), 16 MD and 16 LD runners were assessed. Relationships existed between pion and VO[2max] (r = -0.72, P = 0.002), V[t] (r = -0.66, P = 0.006) and RE (r = -0.59, P = 0.016) in LD runners, but not in MD runners (P >0.05). In addition, pion was related to the volume of training in MD (r = -0.63 , P = 0.009) and LD runners (r = -0.65, P = 0.006).The importance of VO[2] kinetics for 5 km running performance was investigated in 36 endurance trained runners. Runners were categorised as high n=10), low (n=10) and combined [MD + LD (n=36)] performers according to running ability after performing a self-paced 5 km time-trial. Mean (+/-SD) speed for the 5 km time-trial was 5.2 +/-1.0 m-s[-1] (high), 4.5 +/- 0.2 m-s[-1] (low) and 4.9 +/- 0.3 m-s[-1] (combined). Measures of on- and off- transient VO[2] kinetics, VO[2max], V[t] and RE were also determined. Data were explored using bi-variate correlations, ANCOVA and multiple regression techniques. In high and low performers, V0[2] kinetic parameters were not related to running performance. In combined runners, pion, pioff, MRT[on] and MRT[off] were related (r = -0.54, P = 0.001; r = -0.36, P = 0.030; r = -0.50, P = 0.002; r = -0.63, P = 0.003) to running performance. Stepwise multiple regression models were used to identify the primary determinant(s) of 5 km running performance for each group. In high performers, VO[2Max] and RE were included in the model (r = 0.92, R = 0.85, SEE = 0.08 m-s[-1]; SEE% = 1.5). In low performers, VO[2Max] was included in the model (r = 0.76, R[2] = 0.57, SEE = 0.15 m-s[-1], SEE% = 3.3). In combined runners, V0[2Max] RE and MR[off] were included in the model (r = 0.87, R-2 = 0.75, SEE = 0.17 m-s[-1], SEE% = 3.5).Collectively, the results suggest that: 1) VO[2] kinetics can be reproducibly determined using a single visit protocol; 2) measures of VO[2] kinetics are sensitive enough to differentiate MD and LD runners; 3) relationships between VO[2] kinetics and other measures of aerobic function exist in LD runners, but not in MD runners; 4) VO[2] kinetics differ between high and low performers, but do not relate to running performance and 5) VO[2] kinetics discriminate between high and low performers but only contribute minimally to the prediction of running performance in a multiple regression model for combined MD and LD runners.