• The Application of Critical Power, the Work Capacity above Critical Power (W'), and its Reconstitution: A Narrative Review of Current Evidence and Implications for Cycling Training Prescription

      Chorley, Alan; Lamb, Kevin L; University of Chester
      The two-parameter critical power (CP) model is a robust mathematical interpretation of the power–duration relationship, with CP being the rate associated with the maximal aerobic steady state, and W' the fixed amount of tolerable work above CP available without any recovery. The aim of this narrative review is to describe the CP concept and the methodologies used to assess it, and to summarize the research applying it to intermittent cycle training techniques. CP and W' are traditionally assessed using a number of constant work rate cycling tests spread over several days. Alternatively, both the 3-min all-out and ramp all-out protocols provide valid measurements of CP and W' from a single test, thereby enhancing their suitability to athletes and likely reducing errors associated with the assumptions of the CP model. As CP represents the physiological landmark that is the boundary between heavy and severe intensity domains, it presents several advantages over the de facto arbitrarily defined functional threshold power as the basis for cycle training prescription at intensities up to CP. For intensities above CP, precise prescription is not possible based solely on aerobic measures; however, the addition of the W' parameter does facilitate the prescription of individualized training intensities and durations within the severe intensity domain. Modelling of W' reconstitution extends this application, although more research is needed to identify the individual parameters that govern W' reconstitution rates and their kinetics
    • The effects of a cycling warm-up including high-intensity heavy-resistance conditioning contractions on subsequent 4 km time trial performance

      Chorley, Alan; Lamb, Kevin L.; University of Chester (National Strength and Conditioning Association, 2017-03-25)
      Prior exercise has been shown to improve subsequent performance via different mechanisms. Sport-specific conditioning contractions can be used to exploit the 'post-activation potentiation' (PAP) phenomenon to enhance performance although this has rarely been investigated in short endurance events. The aim of this study was to compare a cycling warm-up with PAP-inducing conditioning contractions (CW) with a moderate intensity warm-up (MW) on performance and physiological outcomes of 4 km time trial. Ten well-trained male endurance cyclists (V[Combining Dot Above]O2max 65.3 +/- 5.6 ml[middle dot]kg-1[middle dot]min-1) performed two 4 km cycling time trials following a 5-minute recovery after a warm-up at 60% of V[Combining Dot Above]O2max for 6.5-minutes (MW), and a warm-up with conditioning contractions (CW) consisting of 5 minutes at 60% of V[Combining Dot Above]O2max then 3 x 10-seconds at 70% of peak power interspersed with 30-seconds recovery. Blood lactate concentrations were measured before and after time trial. Expired gases were analysed along with time, power output (PO), and peak forces over each 500 m split. Following CW, mean completion time was reduced (1.7 +/- 3.5 s p > 0.05), PO increased (5.1 +/- 10.5 W p > 0.05) as did peak force per pedal stroke (5.7 +/- 11 N p > 0.05) when compared to MW. V[Combining Dot Above]O2 increased (1.4 +/- 1.6 ml[middle dot]kg-1[middle dot]min-1 p < 0.05) following CW, whilst RER decreased (0.05 +/- 0.02 p < 0.05). Physiological and performance differences following CW were greatest over the first 1500 m of the trials. The results suggest a PAP-inducing warm-up alters V[Combining Dot Above]O2 kinetics and can lead to performance improvements in short endurance cycling but work and recovery durations should be optimised for each athlete.
    • Physiological and anthropometric determinants of critical power, W′ and the reconstitution of W′ in trained and untrained male cyclists

      Chorley, Alan; Bott, Richard P; Marwood, Simon; Lamb, Kevin L; University of Chester (Springer, 2020-08-09)
      Abstract Purpose This study examined the relationship of physiological and anthropometric characteristics with parameters of the critical power (CP) model, and in particular the reconstitution of W′ following successive bouts of maximal exercise, amongst trained and untrained cyclists. Methods Twenty male adults (trained nine; untrained 11; age 39 ± 15 year; mass 74.7 ± 8.7 kg; V̇O2max 58.0 ± 8.7 mL kg−1 min−1) completed three incremental ramps (20 W min−1) to exhaustion interspersed with 2-min recoveries. Pearson’s correlation coefficients were used to assess relationships for W′ reconstitution after the first recovery (W′rec1), the delta in W′ reconstituted between recoveries (ΔW′rec), CP and W′. Results CP was strongly related to V̇O2max for both trained (r = 0.82) and untrained participants (r = 0.71), whereas W′ was related to V̇O2max when both groups were considered together (r = 0.54). W′rec1 was strongly related to V̇O2max for the trained (r = 0.81) but not untrained (r = 0.18); similarly, ΔW′rec was strongly related to V̇O2max (r = − 0.85) and CP (r = − 0.71) in the trained group only. Conclusions Notable physiological relationships between parameters of aerobic fitness and the measurements of W′ reconstitution were observed, which differed among groups. The amount of W′ reconstitution and the maintenance of W′ reconstitution that occurred with repeated bouts of maximal exercise were found to be related to key measures of aerobic fitness such as CP and V̇O2max. This data demonstrates that trained cyclists wishing to improve their rate of W′ reconstitution following repeated efforts should focus training on improving key aspects of aerobic fitness such as V̇O2max and CP.
    • Slowing the Reconstitution of W′ in Recovery With Repeated Bouts of Maximal Exercise

      Chorley, Alan; Bott, Richard; Marwood, Simon; Lamb, Kevin L.; University of Chester; Liverpool Hope University (Human Kinetics, 2019-02-01)
      Purpose: This study examined the partial reconstitution of the work capacity above critical power (W′) following successive bouts of maximal exercise using a new repeated ramp test, against which the fit of an existing W′ balance (W'bal) prediction model was tested. Methods: Twenty active adults, consisting of trained cyclists (n = 9; age 43 [15] y, V˙ O2max 61.9 [8.5] mL·kg−1·min−1) and untrained cyclists (n = 11; age 36 [15] y, V˙ O2max 52.4 [5.8] mL·kg−1·min−1) performed 2 tests 2 to 4 d apart, consisting of 3 incremental ramps (20 W·min−1) to exhaustion interspersed with 2-min recoveries. Results: Intratrial differences between recoveries demonstrated significant reductions in the amount of W′ reconstituted for the group and both subsets (P < .05). The observed minimal detectable changes of 475 J (first recovery) and 368 J (second recovery) can be used to monitor changes in the rate of W′ reconstitution in individual trained cyclists. Intertrial relative reliability of W′ reconstitution was evaluated by intraclass correlation coefficients for the group (≥.859) and the trained (≥.940) and untrained (≥.768) subsets. Absolute reliability was evaluated with typical error (TE) and coefficient of variation (CV) for the group (TE ≤ 559 J, CV ≤ 9.2%), trained (TE ≤ 301 J, CV ≤ 4.7%), and untrained (TE ≤ 720 J, CV ≤ 12.4%). Conclusions: The reconstitution of W′ is subject to a fatiguing effect hitherto unaccounted for in W'bal prediction models. Furthermore, the W'bal model did not provide a good fit for the repeated ramp test, which itself proved to be a reliable test protocol.