Methods

5.2.1 Participants

Fourteen male well-trained competitive club rowers volunteered to take part in the study. Mean age [± standard deviation (SD)] of the participants was 22.8 (5.1) years, stature 1.86 (0.05) m, body mass 85.6 (8.3) kg, 2000 m rowing ergometer time 6:33.9 (0:09.5) min:s, rowing experience 7.1 (5.1) years. All participants had extensive prior experience at performing 2000 m ergometer tests before their involvement in the study. Participants were informed of the experimental procedures and any potential risks involved and gave their written informed consent to participate in the study. The study was approved by the Research Ethics Committee of the School of Life Sciences at Northumbria University.

5.2.2 Experimental protocol

The study followed a repeated measures design to determine the consistency of assessments of strength and power, markers of muscle damage and pacing and metabolic responses during 2000 m rowing ergometry in trained rowers. Each participant performed three laboratory testing sessions interspersed by 3-7 days between each session, each session followed the same protocol which is described below. Participants were asked to arrive at the laboratory in a hydrated state having abstained from exercise on the day of testing and strength training in the 72 h before testing. On the first testing session body mass and stature were measured. A capillary blood sample was taken from the finger for assessment of CK (only sessions 2 and 3) and [Lac-]. Participants perceived soreness rating and limb girths were also assessed. Electrodes were then attached to seven anatomical sites for EMG analysis. Following this, participants completed a five min warm-up on a rowing ergometer, before undertaking a protocol of strength and power tests which involved;

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assessment of maximal voluntary contraction force of the leg extensors, three individual static squat jumps and counter movement jumps, and five maximal rowing power strokes on the rowing ergometer. A face mask was then placed on the participants for analysis of expired breath-by-breath respiratory gas exchange parameters which were to be collected during the 2000 m test. The participants were then instructed to warm-up for a further five min on the rowing ergometer after which they performed the 2000 m test. Heart rate [beats per min (b.min-1)] was recorded every 10 s during the test while immediately after the test, participants provided a rating of perceived exertion (RPE) and capillary blood samples were taken before the test and at 1-, 3-, 5- and 7 min after for the assessment of blood lactate.

5.2.3 Experimental test battery

5.2.3.1 Maximal voluntary contraction (MVC)

Maximal voluntary contraction force of the right leg knee extensors was determined using a strain gauge (MIE Medical Research Ltd, Leeds, UK). Please refer to section 3.4.1 for more detail.

5.2.3.2 Static squat jump (SSJ) and counter movement jump (CMJ)

An optical measurement system (Optojump Next, Microgate, Bolzano, Italy) was used for assessment of jump performance. Three independent SSJ and CMJ trials were conducted; the highest trial was recorded for data analysis. Please refer to section 3.4.2 for more detail.

5.2.3.3 Power strokes (PS)

Maximal stroke power was assessed air-braked rowing ergometer (Concept 2 Model C, Concept 2 Ltd, Wilford, Notts, UK). Please refer to section 3.4.3 for more detail.

5.2.3.4 2000 m rowing ergometer test

The test was performed on an air-braked rowing ergometer (Concept 2 Model C, Concept 2 Ltd, Wilford, Notts, UK). Please refer to section 3.5 for more detail.

5.2.3.5 Surface electromyography analysis (EMG)

Surface EMG was recorded from seven anatomical sites; gastrocnemius (GA), biceps femoris (BF), gluteus maximus (GM), erector spinae (ES), vastus medialis (VM), rectus abdominis (RA) and latissimus dorsi (LD) respectively, and measured during power strokes and the 2000 m test using a 16 channel wireless telemetric system (Myon, Myon AG, Barr, Switzerland). Mean rectified EMG recorded during each 500 m stage of the 2000 m test was normalised against the mean rectified EMG recorded during the five

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power strokes, and subsequently expressed as a percentage. Please refer to section 3.5.7 for more detail.

5.2.3.6 Force analysis

Handle force was recorded during the power strokes and 2000 m test via a load cell (RLTO500kg, RDP Electronics Ltd, Wolverhampton, UK) located in series between the handle and drive chain. The handle force characteristics assessed for power strokes were maximal instantaneous force and power and mean force and power, characteristics assessed during the 2000 m test were mean handle force and power. Please refer to section 3.5.8 for more detail.

5.2.3.7 Rating of perceived soreness

Participants‘ level of perceived muscle soreness was assessed via a 10 cm long visual analogue scale. Please refer to section 3.6.1 for more detail.

5.2.3.8 Limb girths

Limb girth measurements were taken from the mid-thigh, mid-calf and upper arm. Please refer to section 3.6.2 for more detail.

5.2.4 Blood analysis

Capillary blood samples were collected as outlined in section 3.7. This was used for the analysis of blood lactate [Lac-] (section 3.7.1) and CK (section 3.7.2).

5.2.5 Statistical analysis

Descriptive statistics are presented as mean (± SD) unless otherwise stated. Statistical analyses were conducted using SPSS 16.0 (Chicago, IL, USA) with the alpha level for significance set at p < 0.05. One-way ANOVA tests with three repeated measures were used to investigate between trial differences in 2000 m whole trial performance with accompanying physiological measures and also strength and power test performance and markers of muscle damage. Typical error as a percentage (TE %) [90 % confidence intervals (CI)] for the aforementioned assessments was derived from log transformed data and established using a spreadsheet (Hopkins, 2007a). In assessing the variability of performance tests and physiological measures, low and moderate TE have been defined as under 2 % (Hopkins et al., 2001; Stone et al., 2011) and between 3-10 % (Stone et al., 2011) respectively. Smallest practical effect was calculated for each performance test and marker of muscle damage from the product of 0.3 [which represents the smallest standardised change in mean for a group of trained participants; Hopkins et al. (2009)] multiplied by the between-participant standard deviation across the three trials.

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To describe any differences in the pacing strategy, the test data was divided into 4x 500 m stages. A 3x4 (trial x stage) repeated measures ANOVA was used to investigate differences in pacing strategy, which featured assessment of contributions from aerobic (Paer) and anaerobic metabolism (Panaer) to mean power (Ptot), VO2 (L.min-1), stroke rate

[(strokes per min (s.min-1)], handle force and power and EMG. Assumptions of sphericity were assessed using Mauchly‘s test of sphericity, with any violations adjusted by use of the Greenhouse-Geisser (GG) correction. If a significant main effect across time was shown then

post-hoc differences across trials were analysed with use of the LSD correction. Effect size (ES) was calculated for any non-statistically significant result trends (p = 0.051-0.10) in accordance to procedures suggested by Hopkins (2003). In accordance with these procedures interpretation of observed effect sizes are as follows; trivial < 0.2, small 0.2- 0.6, moderate 0.6-1.2, large 1.2-2.0, very large > 2.0 (Hopkins, 2003).