Biology subjects

Samozino, P.

Publications and source records attributed to Samozino, P..

4 recordsLinked to original sources

bioRxiv2025

RACLET: the Ramp Above Critical Level Endurance Test to evaluate critical force in isometric task.

The Ramp Above Critical Level Endurance Test (RACLET) is a novel submaximal test designed to evaluate the parameters of the critical force model without strenuous exercise. This study aimed to validate the RACLET in healthy and pathological populations and to assess its reliability, concurrent validity, and predictive capacity. Sixteen healthy volunteers and ten patients with respiratory pathologies participated in this study. The RACLET consisted of a decreasing ramp force starting at 60% and ending at 15% of the maximum force for a total duration of 425 s with brief regular maximal voluntary contractions. The goodness of fit for the RACLET model on the maximal contraction force was excellent in both populations (median r2{approx} 0.95). In patients, RACLET parameters demonstrated excellent reliability (ICC > 0.90). The concurrent validity of the critical force estimate compared with the all-out method was high (error: -0.3{+/-}7.4%). The models predictive capacity for time-to-exhaustion and fatigue during constant-intensity exercise was excellent (r2 = 0.910 and 0.907, respectively). The RACLET provides a reliable and valid estimate of critical force model parameters opening up numerous practical applications in vulnerable populations, individualised physical activity programs, and longitudinal monitoring. The feasibility and performance of the test make it a promising tool for assessing muscle function in various contexts.

biophysics↗

bioRxiv2025

RACLET: the Ramp Above Critical Level Endurance Test to evaluate critical power in cycling.

This study introduces the Ramp Above Critical Level Endurance Test (RACLET), a novel method for evaluating critical power model parameters, and tests its reliability and concurrent validity. Twenty-three participants completed several RACLET and time-to-exhaustion tests (TTE). The RACLET involves a decreasing power ramp with intermittent maximal sprints, inducing moderate fatigue without exhaustion. The test demonstrated excellent reliability for the initial power (Pi) and critical power (Pc) (ICC > 0.97), with acceptable reliability for the time constant ({tau}) (ICC = 0.70). The concurrent validity against TTE was excellent for Pi and Pc (systematic errors: 1.7% and 3.0%, respectively), but moderate for{tau} and maximum work above the critical power (systematic errors {approx} 10%). The RACLET showed excellent predictive capacity for time-to-exhaustion (systematic error = -0.6%; random error = 10.3%). These results suggest that the RACLET is a reliable, valid, and efficient alternative to traditional critical power testing methods, offering comparable accuracy with a single test without inducing exhaustion. This approach could be particularly beneficial for populations in which exhaustive testing is challenging or impractical.

biophysics↗

bioRxiv2025

RACLET: the Ramp Above Critical Level Endurance Test to evaluate critical velocity in running.

Critical velocity (Vc) is an important fatigability threshold in running, but only strenuous methods exist to assess it (e.g. time-trials). Based on a novel mathematical model of fatigability, the Ramp Above Critical Level Endurance Test (RACLET), a simple, non-exhaustive, 5-min test to evaluate Vc was developed. This study aimed to test the reliability and validity of the RACLET. Thirty-eight participants performed two RACLET (session 1) and three time-trials (sessions 2-4). For the RACLET, velocity target tracking was guaranteed by either a pacing bike or cones and whistle signals. GPS was used to measure the participants running velocities. Vc,{tau} , and [Formula] were determined by adjusting the fatigability model on the measured Vmax. The RACLET test-retest and RACLET vs. time-trials parameters were compared for reliability and validity testing, respectively. The RACLET Vc is reliable and valid (mean difference=-1.7{+/-}1.9% and 6.2{+/-}6.5%, respectively). Although{tau} and [Formula] presented important variability (s.d. difference ~30%), the combination of the RACLET parameters enabled an excellent prediction of time-trials performance (mean error=-8.9{+/-}5.1%, 0.9{+/-}7.4%, -2.0{+/-}5.2% for 400, 1500, and 3000 m, respectively). RACLET is a novel non-exhausting test that enables a reliable and valid assessment of the velocity-time relationship parameters.

biophysics↗

bioRxiv2025

A single decreasing ramp friction sprint for torque-cadence relationship assessment during cycling

This study aimed to introduce and validate a novel method for assessing dynamic fatigue components through a single-sprint test, addressing the limitations of traditional multi-sprint evaluations. We tested this method on twenty-one participants by computing torque-cadence relationships from two iso-friction sprints at varying friction levels (3% and 9% of body mass), the traditional combination of these iso-friction sprints and a novel decreasing ramp friction sprint (FrD). The accuracy of this new method through fatigue was also tested with ten 6-s FrD sprints interspersed with a 24-s passive rest. FrD outperformed single iso-friction sprints and provided accurate and valid torque-cadence relationships parameters estimates (T0, C0, and Pmax) with systematic bias < 3%, typical error of estimate < 6% and very high r2 (median of 0.962). The quality of the input data from this method was also high, as evidenced by the well-distributed and wide-range cadence spectrum (51.3% of C0; skewness = -0.51, p < 0.05) and was maintained throughout the fatiguing exercise. Our novel method not only allows the dynamic fatigue components evaluation with only one sprint but also maintains accuracy and validity across varying fatigue states, offering significant advantages for both research and practical applications.

physiology↗