Force-velocity test on a stationary cycle ergometer: methodological recommendations

The influence of cadence on fatigue during maximal sprint cycling in world-class and elite sprint cyclists

Optimising cadence through appropriate gear selection is a key consideration for track sprint cycling performance, yet the influence of cadence on fatigue (i.e., decrement in power output) within a maximal sprint is not well understood. The aim of this study was to identify the influence of cadence on fatigue during maximal sprint cycling. Eleven world-class and elite track sprint cyclists (n = 6 men, maximal power output (Pmax) = 1894 ± 351 W, optimal cadence (Fopt) = 134 ± 8 rev∙min-1: n = 5 women, Pmax = 1114 ± 80 W, Fopt = 124 ± 8 rev∙min-1) completed two testing sessions where power-cadence profiles were constructed to determine the Fopt associated with Pmax. Cyclists also performed three maximal 15-s sprints (Fopt, ±15%Fopt) to identify fatigue per pedal stroke across these cadence ranges. There was no significant difference (p = 0.2) in the absolute fatigue per pedal stroke when cadence was fixed 15% above (16.7 ± 6.1 W∙stroke-1) and below (15.3 ± 5.1 W∙stroke-1) Fopt. Similarly, there was no significant difference in the relative fatigue per pedal stroke (% peak power∙stroke-1) across Fopt and ± 15%Fopt trials (p = 0.12). The relative decrement in power output is equivalent across the ± 15%Fopt cadence range. As such, a higher-geared, lower-cadence approach to maximal sprint cycling could be a viable method to minimise maximal pedal strokes and reduce the decrement in power output.

Field- and Laboratory-derived Power-Cadence Profiles in World-Class and Elite Track Sprint Cyclists

Previous investigations comparing Torque-Cadence (T-C) and Power-Cadence (P-C) profiles derived from seated and standing positions and field and laboratory conditions are not congruent with current methodological recommendations. Consequently, the aim of this investigation was to compare seated and standing T-C and P-C profiles generated from field and laboratory testing. Thirteen world-class and elite track sprint cyclists (n = 7 males, maximal power output (Pmax) = 2112 ± 395 W; n = 6 females, Pmax = 1223 ± 102 W) completed two testing sessions in which field- and laboratory-derived T-C and P-C profiles were identified. Standing P-C profiles had significantly (p < 0.05) greater Pmax than seated profiles, however there were no significant differences in optimal cadence (Fopt) between seated and standing positions. Pmax and Fopt were significantly lower in field-derived profiles in both positions compared to laboratory-derived profiles. However, there was no significant difference in the goodness-of-fit (R2) of the P-C profiles between laboratory (0.985 ± 0.02) and field-testing (0.982 ± 0.02) in each position. Valid T-C and P-C profiles can be constructed from field and laboratory protocols; however, the mechanical variables derived from the seated and standing and field and laboratory profiles cannot be used interchangeably. Both field and laboratory-derived profiles provide meaningful information and provide complementary insights into cyclists' capacity to produce power output.

Exploring the Low Force-High Velocity Domain of the Force-Velocity Relationship in Acyclic Lower-Limb Extensions

PURPOSE

To compare linear and curvilinear models describing the force-velocity relationship obtained in lower-limb acyclic extensions, considering experimental data on an unprecedented range of velocity conditions.

METHODS

Nine athletes performed lower-limb extensions on a leg-press ergometer, designed to provide a very broad range of force and velocity conditions. Previously inaccessible low inertial and resistive conditions were achieved by performing extensions horizontally and with assistance. Force and velocity were continuously measured over the push-off in six resistive conditions to assess individual force-velocity relationships. Goodness of fit of linear and curvilinear models (second-order polynomial function, Fenn and Marsh's, and Hill's equations) on force and velocity data were compared via the Akaike Information Criterion.

RESULTS

Expressed relative to the theoretical maximal force and velocity obtained from the linear model, force and velocity data ranged from 26.6 ± 6.6 to 96.0 ± 3.6% (16-99%) and from 8.3 ± 1.9 to 76.6 ± 7.0% (5-86%), respectively. Curvilinear and linear models showed very high fit (adjusted r2 = 0.951-0.999; SEE = 17-159N). Despite curvilinear models better fitting the data, there was a ~ 99-100% chance the linear model best described the data.

CONCLUSION

A combination between goodness of fit, degrees of freedom and common sense (e.g., rational physiologically values) indicated linear modelling is preferable for describing the force-velocity relationship during acyclic lower-limb extensions, compared to curvilinear models. Notably, linearity appears maintained in conditions approaching theoretical maximal velocity. Using horizontal and assisted lower-limb extension to more broadly explore resistive/assistive conditions could improve reliability and accuracy of the force-velocity relationship and associated parameters.

Determination of optimal load in the Wingate Anaerobic Test is not depend on number of sprints included in mathematical models

Determining the optimal load (OPT_LOAD) in measuring mechanical peak power output (PPO) is important in assessment of anaerobic fitness. The main goals of this study were: 1) to examine estimated optimal load and PPO based on a force-velocity test and 2) to compare the PPO from the previous method with the Wingate Anaerobic Test (WAnT). The study involved 15 academic male athletes, aged 22.4 ± 2.3 (years), height 178.9 ± 6.8 (cm), and body weight 77.9 ± 12.2 (kg). They performed the 30-s WAnT (7.5% of body weight) during the first visit to the laboratory. Second to fourth session included a force-velocity test (FVT) involving three, 10-s all-out sprints. A randomized load ranging from 3 to 11 kg was used in each session for FVT. The OPT_LOAD and PPO were computed using quadratic relationships based on power-velocity (P-v) and power-percent of body weight (P-%BM) and including three, four, five and nine sprints from FVT. The results showed non-difference in OPT_LOAD [13.8 ± 3.2 (%BM); 14.1 ± 3.5 (%BM); 13.5 ± 2.8 (%BM); 13.4 ± 2.6 (%BM)] executed at three, four, five, and nine sprints (F_3,56 = 0.174, p = 0.91, η² = 0.01). The two-way ANOVA revealed that PPO were similar between tested models (P-%BM vs. P-v) independently from the numbers of sprints (F_3,112 = 0.08, p = 0.99, η² = 0.000). Moreover, the PPO measured in the WAnT (870.6 ± 179.1 W) was significantly lower compared with in P-v model (1,102.9 ± 242.5-1,134.2 ± 285.4 W) (F_4,70 = 3.044, p = 0.02, η² = 0.148). In addition, the PPO derived from P-%BM model (1,105.2 ± 245.5-1,138.7 ± 285.3 W) was significantly higher compared with the WAnT (F_4,70 = 2.976, p = 0.02, η² = 0.145). The findings suggest the potential utility of FVT for assessment of anaerobic capacity.

Force-velocity profiles of track cyclists differ between seated and non-seated positions

The aim of the study was to compare the Force-Velocity profiles of track sprint cyclists obtained in seated and non-seated positions. Athletes were tested on a stationary cycle ergometer for the seated position and on a racing bike at the velodrome for the non-seated position. We modelled torque and power vs. cadence relationships and extracted maximal force (F₀), optimal cadence (C_opt), maximal power (P_max), maximal cadence (C₀) and C_opt/C₀ ratio. Torque/power production was larger in the non-seated position for cadences ranging from 20 to 120 rpm, while more torque and power were produced in the seated position at cadences above 160 rpm. The effective pedal force increased by 0.2 times bodyweight at 50 rpm, and the power production increased by 2.5 W. kg^-1 at   90 rpm in the non-seated position. C_opt (-14 ± 8 rpm, P < 0.05) and C₀ (-55 ± 32 rpm, P < 0.05) were lowered, while P_max (+1.7 ± 1.1 W. kg^-1, P < 0.05) and C_opt/C₀ ratios (+0.07 ± 0.04, P < 0.05) were increased in the non-seated position when compared with the seated position. Our results show that adopting a non-seated position allows sprint cyclists to maximise torque/power production at lower cadences, while torque/power production was maximised at higher cadences when athletes adopted a seated position.

Sprint cycling rate of torque development associates with strength measurement in trained cyclists

PURPOSE

A cyclist's rate of force/torque development (RFD/RTD) and peak force/torque can be measured during single-joint or whole-body isometric tests, or during cycling. However, there is limited understanding of the relationship between these measures, and of the mechanisms that contribute to each measure. Therefore, we examined the: (i) relationship between quadriceps central and peripheral neuromuscular function with RFD/RTD in isometric knee extension, isometric mid-thigh pull (IMTP), and sprint cycling; and (ii) relationship among RFD/RTD and peak force/torque between protocols.

METHODS

Eighteen trained cyclists completed two familiarisation and two experimental sessions. Each session involved an isometric knee extension, IMTP, and sprint cycling protocol, where peak force/torque, average and peak RFD/RTD, and early (0-100 ms) and late (0-200 ms) RFD/RTD were measured. Additionally, measures of quadriceps central and peripheral neuromuscular function were assessed during the knee extension.

RESULTS

Strong relationships were observed between quadriceps early EMG activity (EMG₅₀/M) and knee extension RTD (r or ρ = 0.51-0.65) and IMTP late RFD (r = 0.51), and between cycling early or late RTD and peak twitch torque (r or ρ = 0.70-0.75). Strong-to-very strong relationships were observed between knee extension, IMTP, and sprint cycling for peak force/torque, early and late RFD/RTD, and peak RFD/RTD (r or ρ = 0.59-0.80).

CONCLUSION

In trained cyclists, knee extension RTD or IMTP late RFD are related to measures of quadriceps central neuromuscular function, while cycling RTD is related to measures of quadriceps peripheral neuromuscular function. Further, the strong associations among force/torque measures between tasks indicate a level of transferability across tasks.

Fatigue-Free Force-Velocity and Power-Velocity Profiles for Elite Track Sprint Cyclists: The Influence of Duration, Gear Ratio and Pedalling Rates

Background: Maximal force-velocity (F/v) profiles for track cyclists are commonly derived from ergometer sprints using an isovelocity or isoinertial approach. Previously, an attempt was made to derive maximal F/v profiles from a single maximal 65-m sprint on the cycling track. Hypothesising that this approach may not accurately reflect the fatigue-free F/v profile, we propose an alternative procedure and compare it to the previous method. Moreover, we test for the impact of gear ratio on diagnostic results. Methods: Twelve elite track cyclists completed a high-cadence low-resistance pedalling test on a freestanding roller (motoric test) and two series of three maximal 65-m sprints on a cycling track with different gear ratios. F/v profiles were calculated based on the measured crank force and cadence either during the first 6−7 revolutions (≤6 s) on the track (model I) or were derived from the first 3−4 revolutions (≤3 s) on the track combined with 1 or 2 fatigue-free cycles at cadences above 160 rpm from the motoric test (model II). Results: Although both models exhibit high-to-excellent linearity between force and velocity, the extrapolated isometric force was higher (1507.51 ± 257.60 N and 1384.35 ± 276.84 N; p < 0.002; d = 2.555) and the slope steeper (−6.78 ± 1.17 and −5.24 ± 1.11; p < 0.003, d = −2.401) with model I. An ICC of 1.00 indicates excellent model consistency when comparing the F/v profiles (model II) derived from the different geared sprints. Conclusions: Assuring fatigue-free measurements and including high-cadence data points in the calculations provide valid maximal F/v and P/v profiles from a single acceleration-sprint independent of gear ratio.

The balancing act: Identifying multivariate sports performance using Pareto frontiers

Athletes often require a mix of physical, physiological, psychological, and skill-based attributes that can be conflicting when competing at the highest level within their sport. When considering multiple variables in tandem, Pareto frontiers is a technique that can identify the observations that possess an optimal balance of the desired attributes, especially when these attributes are negatively correlated. This study presents Pareto frontiers as a tool to identify athletes who possess an optimal ranking when considering multiple metrics simultaneously. This study explores the trade-off relationship between batting average and strike rate as well as bowling strike rate, economy, and average in Twenty 20 cricket. Eight hundred ninety-one matches of Twenty 20 cricket from the men's (MBBL) and women's (WBBL) Australian Big Bash Leagues were compiled to determine the best batting and bowling performances, both within a single innings and across each player's Big Bash career. Pareto frontiers identified 12 and seven optimal batting innings performances in the MBBL and WBBL respectively, with nine and six optimal batting careers respectively. Pareto frontiers also identified three optimal bowling innings in both the MBBL and WBBL and five and six optimal bowling careers in MBBL and WBBL, respectively. Each frontier identified players that were not the highest ranked athlete in any metric when analyzed univariately. Pareto frontiers can be used when assessing talent across multiple metrics, especially when these metrics may be conflicting or uncorrelated. Using Pareto frontiers can identify athletes that may not have the highest ranking on a given metric but have an optimal balance across multiple metrics that are associated with success in a given sport.

Assessing rate of torque development in sprint cycling: a methodological study

AbstractThe present study examined (i) the magnitude of rate of torque development (RTD), and (ii) the between-day reliability of RTD at the start of a cycling sprint when sprint resistance, sprint duration, and the pedal downstroke were altered. Nineteen well-trained cyclists completed one familiarisation and three testing sessions. Each session involved one set of 1-s sprints and one set of 5-s sprints. Each set contained one moderate (0.3 Nm.kg^-1), one heavy (0.6 Nm.kg^-1), and one very heavy (1.0 Nm.kg^-1) resistance sprint. RTD measures (average and peak RTD, RTD 0-100 ms, and RTD 0-200 ms) were calculated for downstroke 1 in the 1-s sprint. For the 5-s sprints, RTD measures were calculated for each of the first three downstrokes, as an average of downstrokes 1 and 2, and as an average of downstrokes 2 and 3. Whilst RTDs were greatest in downstroke 3 at all resistances, the greatest number of reliable RTD measures were obtained using the average of downstrokes 2 and 3 with heavy or very heavy resistances, where average and peak RTD, and RTD 0-200 ms were deemed reliable (ICC ≥ 0.8, CV ≤ 10%). Since only 1 - 2 downstrokes can be completed within 1 s, the greatest RTD reliability cannot be achieved using a 1-s sprint; therefore, the average of downstrokes 2 and 3 during a >2-s cycling sprint (e.g., 5-s test) with heavy or very heavy resistance is recommended for the assessment of RTD in sprint cyclists.

A critical review of critical power

The elegant concept of a hyperbolic relationship between power, velocity, or torque and time to exhaustion has rightfully captivated the imagination and inspired extensive research for over half a century. Theoretically, the relationship's asymptote along the time axis (critical power, velocity, or torque) indicates the exercise intensity that could be maintained for extended durations, or the "heavy-severe exercise boundary". Much more than a critical mass of the extensive accumulated evidence, however, has persistently shown the determined intensity of critical power and its variants as being too high to maintain for extended periods. The extensive scientific research devoted to the topic has almost exclusively centered around its relationships with various endurance parameters and performances, as well as the identification of procedural problems and how to mitigate them. The prevalent underlying premise has been that the observed discrepancies are mainly due to experimental 'noise' and procedural inconsistencies. Consequently, little or no effort has been directed at other perspectives such as trying to elucidate physiological reasons that possibly underly and account for those discrepancies. This review, therefore, will attempt to offer a new such perspective and point out the discrepancies' likely root causes.

Quadriceps Muscle Fatigue Reduces Extension and Flexion Power During Maximal Cycling

Purpose: To investigate how quadriceps muscle fatigue affects power production over the extension and flexion phases and muscle activation during maximal cycling.

Methods: Ten participants performed 10-s maximal cycling efforts without fatigue and after 120 bilateral maximal concentric contractions of the quadriceps muscles. Extension power, flexion power and electromyographic (EMG) activity were compared between maximal cycling trials. We also investigated the associations between changes in quadriceps force during isometric maximal voluntary contractions (IMVC) and power output (flexion and extension) during maximal cycling, in addition to inter-individual variability in muscle activation and pedal force profiles.

Results: Quadriceps IMVC (−52 ± 21%, P = 0.002), voluntary activation (−24 ± 14%, P &lt; 0.001) and resting twitch amplitude (−45 ± 19%, P = 0.002) were reduced following the fatiguing task, whereas vastus lateralis (P = 0.58) and vastus medialis (P = 0.15) M-wave amplitudes were unchanged. The reductions in extension power (−15 ± 8%, P &lt; 0.001) and flexion power (−24 ± 18%, P &lt; 0.001) recorded during maximal cycling with fatigue of the quadriceps were dissociated from the decreases in quadriceps IMVC. Peak EMG decreased across all muscles while inter-individual variability in pedal force and EMG profiles increased during maximal cycling with quadriceps fatigue.

Conclusion: Quadriceps fatigue induced by voluntary contractions led to reduced activation of all lower limb muscles, increased inter-individual variability and decreased power production during maximal cycling. Interestingly, power production was further reduced over the flexion phase (24%) than the extension phase (15%), likely due to larger levels of peripheral fatigue developed in RF muscle and/or a higher contribution of the quadriceps muscle to flexion power production compared to extension power during maximal cycling.

Optimal load for a torque-velocity relationship test during cycling

PURPOSE

Lower limbs' neuromuscular force capabilities can only be determined during single sprints if the test provides a good fit of the data in the torque-velocity (T-V) and power-velocity (P-V) relationships. This study compared the goodness of fit of single sprints performed against traditional (7.5% of the body mass) vs. optimal load (calculated based on the force production capacity and ergometer specificities), and examined if reducing the load in fatigued state enhances T-V and P-V relationship goodness of fit.

METHODS

Thirteen individuals performed sprints before (PRE) and after (POST) a fatiguing task against different loads: (1) TRAD: traditional, (2) OPT: optimal, and (3) LOW-OPT: optimal load reduced according to fatigue levels.

RESULTS

At PRE, OPT sprints presented a higher R² of the T-V relationship (0.92 ± 0.06) and lower time to reach maximal power (P_max) (48 ± 9%) when compared with TRAD sprints (0.89 ± 0.06 and 66 ± 22%, respectively, p < 0.01). At POST, the range of velocity spectrum was greater in the LOW-OPT (33 ± 4%) vs. TRAD (24 ± 3%) and OPT (26 ± 8%, p < 0.007). Similarly, the time to reach P_max was lower in the LOW-OPT (46 ± 12%) vs. TRAD (76 ± 24%) and OPT (70 ± 24%, p < 0.006).

CONCLUSION

Sprints performed against an OPT load and reducing the OPT load after fatigue improve the fit of data in the T-V and P-V curves. Sprints load assignment should consider force production capacities rather than body mass.

Quantification of maximal power output in well-trained cyclists

This study aimed to compare mechanical variables derived from torque-cadence and power-cadence profiles established from different cycle ergometer modes (isoinertial and isokinetic) and modelling procedures (second- and third-order polynomials), whilst employing a novel method to validate the theoretical maximal power output (P_max). Nineteen well-trained cyclists (n = 12 males) completed two experimental sessions comprising six, 6-s maximal isoinertial or isokinetic cycling sprints. Maximal pedal strokes were extracted to construct power-cadence relationships using second- and third-order polynomials. A 6-s sprint at the optimal cadence (F_opt) or optimal resistance (T_opt) was performed to assess construct validity of P_max. No differences were found in the mechanical parameters when derived from isokinetic (P_max = 1311 ± 415, F_opt = 118 ± 12) or isoinertial modes (P_max = 1320 ± 421, F_opt = 116 ± 19). However, R² improved (P < 0.02) when derived from isoinertial sprints. Third-order polynomial modelling improved goodness of fit values (Standard Error, adjusted R²), but derived similar mechanical parameters. Finally, peak power output during the optimised sprint did not significantly differ from the theoretical P_max in both cycling modes, thus providing construct validity. The most accurate P-C profile can be derived from isoinertial cycling sprints, modelled using third-order polynomial equations.

Effects of high-intensity intermittent exercise on the contractile properties of human type I and type II skeletal muscle fibers

In vitro studies have shown that alterations in redox state can cause a range of opposing effects on the properties of the contractile apparatus in skeletal muscle fibers. To test whether and how redox changes occurring in vivo affect the contractile properties, vastus lateralis muscle fibers from seven healthy young adults were examined at rest (PRE) and following (POST) high-intensity intermittent cycling exercise. Individual mechanically skinned muscle fibers were exposed to heavily buffered solutions at progressively higher free [Ca²⁺] to determine their force-Ca²⁺ relationship. Following acute exercise, Ca²⁺ sensitivity was significantly decreased in type I fibers (by 0.06 pCa unit) but not in type II fibers (0.01 pCa unit). Specific force decreased after the exercise in type II fibers (-18%) but was unchanged in type I fibers. Treatment with the reducing agent dithiothreitol (DTT) caused a small decrease in Ca²⁺-sensitivity in type II fibers at PRE (by ∼0.014 pCa units) and a significantly larger decrease at POST (∼0.035 pCa units), indicating that the exercise had increased S-glutathionylation of fast troponin I. DTT treatment also increased specific force (by ∼4%), but only at POST. In contrast, DTT treatment had no effect on either parameter in type I fibers at either PRE or POST. In type I fibers, the decreased Ca²⁺ sensitivity was not due to reversible oxidative changes and may have contributed to a decrease in power production during vigorous exercises. In type II fibers, exercise-induced redox changes help counter the decline in Ca²⁺-sensitivity while causing a small decline in maximum force.NEW & NOTEWORTHY This study identified important cellular changes occurring in human skeletal muscle fibers following high-intensity intermittent exercise: 1) a decrease in contractile apparatus Ca²⁺ sensitivity in type I but not type II fibers, 2) a decrease in specific force only in type II muscle fibers, and 3) a redox-dependent increase in Ca²⁺ sensitivity occurring only in type II fibers, which would help maintain muscle performance by countering the normal metabolite-induced decline in Ca²⁺ sensitivity.

Reliability of force-velocity parameters obtained from linear and curvilinear regressions for the bench press and squat exercises

This study aimed to compare the goodness of fit and the reliability of different regression models for fitting the force-velocity relationship (FV) of bench press (BP) and squat (SQ). Additionally, the reliability of the position on FV of the velocity (V_1RM) and the force performed with the 1RM (F_1RM) was explored. Nine rugby players and 12 judokas participated in this study. The FV of BP and SQ were obtained twice by a protocol performed until the 1RM. Individual FV were fitted by linear (LM), quadratic polynomial (PM), and exponential models (EM). Adjusted coefficients of determination of LM and PM (medians higher than 0.919) were higher than for EM. The reliability was higher for LM in comparison with PM. The reliability of V_1RM was not acceptable (CV% = 19 and 18% for BP and SQ). High reliability was observed for F_1RM (CV% = 3 and 2% for BP and SQ) and for the ratio between F_1RM and the force-axis intercept of FV (CV% = 2 and 4% for BP and SQ). The reliability of the relative values of F_1RM around 92 and 87% of F₀ for BP and SQ suggests the use of these values for monitoring resistance training programmes.