Musculotendinous Adaptations to Strength and Endurance Training in Cyclists

Maximal strength (kg) for the leg extension was estimated from a five-repetition maximum (5RM) test conducted according to National Strength and Conditioning Association guidelines in two exercises (barbell squat and leg press). The corresponding 1RM values were estimated using the ExRx.net calculator.

Quadriceps muscle thickness (mm) (vastus lateralis, rectus femoris, vastus medialis) assessed using B-mode ultrasound imaging.

Isometric maximal voluntary contraction (MVC) of the knee extensors assessed using an isokinetic dynamometer (System 3; Biodex Medical Systems, Shirley, NY, USA). Following a 5-min warm-up on a cycle ergometer at a self-selected workload and cadence, participants were seated upright in the dynamometer chair with double shoulder straps securing the upper body and were verbally encouraged to exert maximal effort. Three MVC trials were performed at a knee joint angle of 70 o (full extension = 0 deg) and the highest peak torque (Nm) was used for analysis. Each trial was separated by 1 minute of rest, and two submaximal warm-up contractions were completed before testing.

Isokinetic concentric peak torque of the knee extensors assessed using an isokinetic dynamometer (System 3; Biodex Medical Systems, Shirley, NY, USA). Following a 5-min warm-up on a cycle ergometer at a self-selected workload and cadence, participants were seated upright in the dynamometer chair with double shoulder straps securing the upper body and were verbally encouraged to exert maximal effort. Three maximal concentric contractions performed at a knee joint angle of 70 deg (full extension = 0 deg) and at 60 deg/s, and the highest peak torque (Nm) was used for analysis. Each trial was separated by 1 minute of rest, and two submaximal warm-up contractions were completed before testing.

Patellar tendon morphological changes assessed using B-mode ultrasound imaging - cross-sectional area (square millimetres).

Body mass (kg) assessed using standard anthropometric methods.

Height (cm) assessed using standard anthropometric methods.

Body mass (kg) and height (m) will be used to calculate the body mass index (BMI) (kg/m2).

To estimate body fat (%), skinfold thickness was assessed with a GIMA Skinfold Caliper, featuring a precision of 0.2 mm, at the following sites on the right side of the body: triceps, biceps, mid-axillary, chest, subscapular, abdominal, suprailiac, thigh, and calf. The percentage of fat mass (BF%) were derived using the Jackson and Pollock equation (7-sites) and by the Siri equation. BF% was calculated from body density (BD) using SIRI equation.

For the determination of VO2max, participants initiated with a standardized warm-up at 120 W for 5-min, followed by an incremental ramp test protocol (20 W/min) on an electromagnetically braked ergometer (Lode Excalibur Sport, Lode BV). The cyclists were free to choose their pedaling cadence, and the ergometer's configuration was tailored to individual preferences and requisites. Real-time analysis of gas exchange was conducted using a spiroergometric device operating in breath-by-breath mode (MetaLyzer 3B, Cortex Biophysik), with the gas analyzer calibrated prior to each session. Heart rate was continuously monitored via a chest strap heart rate monitor (Polar H10, Polar Electro). The VO2max was determined as the highest consecutive 30-second rolling average value attained during the test.

For the determination of maximal aerobic power (MAP), participants initiated with a standardized warm-up at 120 W for 5-min, followed by an incremental ramp test protocol (20 W/min) on an electromagnetically braked ergometer (Lode Excalibur Sport, Lode BV). The cyclists were free to choose their pedaling cadence, and the ergometer's configuration was tailored to individual preferences and requisites. The maximal aerobic power (MAP) was identified as the maximum sustained power value achieved for a minimum duration of 1 second during the test. Both variables were quantified i

Cycling gross efficiency (GE) was measured employing the MetaLyzer (MetaLyzer 3B, Cortex Biophysik) for gas exchange analysis and the Excalibur Sport bike ergometer (Lode Excalibur Sport, Lode BV). After a 5-min warm up, participants sustained a consistent cadence of 75±2 rpm while pedaling for 8-min, exerting efforts at intensities corresponding to 45% of the MAP achieved during the maximal incremental exercise test. Gross efficiency (%) was calculated for each stage using the formula: (Total work)/(Energy expended )×100. Data validity was ascertained when the respiratory exchange ratio remained stable below 1, and calculations excluded the initial minute to ensure the attainment of gas exchange plateau.

To ensure procedural familiarity, each athlete participated in two simulation trials (i.e., spinning till sprint start and holding the sprint session for 1-2 seconds approximately) before the official 6-sec sprint commenced. Subsequently, participants exerted their utmost sprinting effort throughout the entire 6 s duration while receiving robust verbal encouragement. The Excalibur Sport bike ergometer (Lode Excalibur Sport, Lode BV) was employed for this sprint test, with the resistance (torque factor) set at 0.75 N×kg-1 of body mass and equipped with cyclist preferred pedals. The resistance was applied with a cadence threshold of 100 rpm, following a 30 s warm-up at 150 W. The sprint 1-s peak power was quantified both in absolute terms and relative to the participant's body mass (W, W/kg).

To ensure procedural familiarity, each athlete participated in two simulation trials (i.e., spinning till sprint start and holding the sprint session for 1-2 seconds approximately) before the official 6-sec sprint commenced. Subsequently, participants exerted their utmost sprinting effort throughout the entire 6 s duration while receiving robust verbal encouragement. The Excalibur Sport bike ergometer (Lode Excalibur Sport, Lode BV) was employed for this sprint test, with the resistance (torque factor) set at 0.75 N×kg-1 of body mass and equipped with cyclist preferred pedals. The resistance was applied with a cadence threshold of 100 rpm, following a 30 s warm-up at 150 W. The sprint 1-s peak crank torque was quantified both in absolute terms and relative to the participant's body mass (Nm, Nm/kg).