Over 55 years of critical power: Fact or artifact?

This report aims to generate an evidence-based debate of the Critical Power (CP), or its analogous Critical Speed (CS), concept. Race times of top Spanish runners were utilized to calculate CS based on three (1500-m to 5000-m; CS1.5-5km ) and four (1500-m to 10000-m; CS1.5-10km ) distance performances. Male running world records from 1000 to 5000-m (CS1-5km ), 1000 to 10,000-m (CS1-10km ), 1000-m to half marathon (CS1km-half marathon ), and 1000-m to marathon (CS1km-marathon ) distance races were also utilized for CS calculations. CS1.5-5km (19.62 km h-1 ) and CS1.5-10km (18.68 km h-1 ) were different (p < 0.01), but both approached the average race speed of the longest distance chosen in the model, and were remarkably homogeneous among subjects (97% ±1% and 98% ±1%, respectively). Similar results were obtained using the world records. CS values progressively declined, until reaching a CS1km-marathon value of 20.77 km h-1 (10% lower than CS1-5km ). Each CS value approached the average speed of the longest distance chosen in the model (96.4%-99.8%). A power function better fitted the speed-time relationship compared with the standardized hyperbolic function. However, the horizontal asymptote of a power function is zero. This better approaches the classical definition of CP: the power output that can be maintained almost indefinitely without exhaustion. Beyond any sophisticated mathematical calculation, CS corresponds to 95%-99% of the average speed of the longest distance chosen as an exercise trial. CP could be considered a mathematical artifact rather than an important endurance performance marker. In such a case, the consideration of CP as a physiological "gold-standard" should be reevaluated.

Effect of velocity loss during squat training on neuromuscular performance.

This study aimed to compare the effects of three resistance training (RT) programs differing in the magnitude of velocity loss (VL) allowed in each exercise set: 10%, 30%, or 45% on changes in strength, vertical jump, sprint performance, and EMG variables. Thirty-three young men were randomly assigned into three experimental groups (VL10%, VL30%, and VL45%; n = 11 each) that performed a velocity-based RT program for 8 weeks using only the full squat exercise (SQ). Training load (55-70% 1RM), frequency (2 sessions/week), number of sets (3), and inter-set recovery (4 min) were identical for all groups. Running sprint (20 m), countermovement jump (CMJ), 1RM, muscle endurance, and EMG during SQ were assessed pre- and post-training. All groups showed significant (VL10%: 6.4-58.6%; VL30%: 4.5-66.2%; VL45%: 1.8-52.1%; p < 0.05-0.001) improvements in muscle strength and muscle endurance. However, a significant group × time interaction (p < 0.05) was observed in CMJ, with VL10% showing greater increments (11.9%) than VL30% and VL45%. In addition, VL10% resulted in greater percent change in sprint performance than the other two groups (VL10%: -2.4%; VL30%: -1.8%; and VL45%: -0.5%). No significant changes in EMG variables were observed for any group. RT with loads of 55-70% 1RM characterized by a low-velocity loss (VL10%) provides a very effective and efficient training stimulus since it yields similar strength gains and greater improvements in sports-related neuromuscular performance (jump and sprint) compared to training with higher velocity losses (VL30%, VL45%). These findings indicate that the magnitude of VL reached in each exercise set considerably influences the observed training adaptations.

Relationship Between Velocity Loss and Repetitions in Reserve in the Bench Press and Back Squat Exercises.

Rodríguez-Rosell, D, Yáñez-García, JM, Sánchez-Medina, L, Mora-Custodio, R, and González-Badillo, JJ. Relationship between velocity loss and repetitions in reserve in the bench press and back squat exercises. J Strength Cond Res 34(9): 2537-2547, 2020-This study aimed to compare the pattern of repetition velocity decline during a single set to failure performed against 4 relative loads in the bench press (BP) and full back squat (SQ) exercises. After an initial test to determine 1 repetition maximum (1RM) strength and load-velocity relationships, 20 men performed one set of repetitions to failure (MNR test) against loads of 50, 60, 70, and 80% 1RM in BP and SQ, on 8 random order sessions performed every 6-7 days. Velocity against the load that elicited a ∼1.00 m·s (V1 m·s load) was measured before and immediately after each MNR test, and it was considered a measure of acute muscle fatigue. The number of repetitions completed against each relative load showed high interindividual variability in both BP (coefficient of variation [CV]: 15-22%) and SQ (CV: 26-34%). Strong relationships were found between the relative loss of velocity in the set and the percentage of performed repetitions in both exercises (R = 0.97 and 0.93 for BP and SQ, respectively). Equations to predict repetitions left in reserve from velocity loss are provided. For a given magnitude of velocity loss within the set (15-65%), the percentages of performed repetitions were lower for the BP compared with the SQ for all loads analyzed. Acute fatigue after each set to failure was found dependent on the magnitude of velocity loss (r = 0.97 and 0.99 for BP and SQ, respectively) but independent of the number of repetitions completed by each participant (p > 0.05) for both exercises. The percentage of velocity loss against the V1 m·s load decreased as relative load increased, being greater for BP than SQ. These findings indicate that monitoring repetition velocity can be used to provide a very good estimate of the number (or percentage) of repetitions actually performed and those left in reserve in each exercise set, and thus to more objectively quantify the level of effort incurred during resistance training.

Time Course of Recovery From Resistance Exercise With Different Set Configurations.

Pareja-Blanco, F, Rodríguez-Rosell, D, Aagaard, P, Sánchez-Medina, L, Ribas-Serna, J, Mora-Custodio, R, Otero-Esquina, C, Yáñez-García, JM, and González-Badillo, JJ. Time course of recovery from resistance exercise with different set configurations. J Strength Cond Res 34(10): 2867-2876, 2020-This study analyzed the response to 10 resistance exercise protocols differing in the number of repetitions performed in each set (R) with respect to the maximum predicted number (P). Ten males performed 10 protocols (R(P): 6(12), 12(12), 5(10), 10(10), 4(8), 8(8), 3(6), 6(6), 2(4), and 4(4)). Three sets with 5-minute interset rests were performed in each protocol in bench press and squat. Mechanical muscle function (countermovement jump height and velocity against a 1 m·s load, V1-load) and biochemical plasma profile (testosterone, cortisol, growth hormone, prolactin, IGF-1, and creatine kinase) were assessed at several time points from 24-hour pre-exercise to 48-hour post-exercise. Protocols to failure, especially those in which the number of repetitions performed was high, resulted in larger reductions in mechanical muscle function, which remained reduced up to 48-hour post-exercise. Protocols to failure also showed greater increments in plasma growth hormone, IGF-1, prolactin, and creatine kinase concentrations. In conclusion, resistance exercise to failure resulted in greater fatigue accumulation and slower rates of neuromuscular recovery, as well as higher hormonal responses and greater muscle damage, especially when the maximal number of repetitions in the set was high.

Velocity- and power-load relationships in the half, parallel and full back squat.

This study aimed to compare the load-velocity and load-power relationships of three common variations of the squat exercise. 52 strength-trained males performed a progressive loading test up to the one-repetition maximum (1RM) in the full (F-SQ), parallel (P-SQ) and half (H-SQ) squat, conducted in random order on separate days. Bar velocity and vertical force were measured by means of a linear velocity transducer time-synchronized with a force platform. The relative load that maximized power output (Pmax) was analyzed using three outcome measures: mean concentric (MP), mean propulsive (MPP) and peak power (PP), while also including or excluding body mass in force calculations. 1RM was significantly different between exercises. Load-velocity and load-power relationships were significantly different between the F-SQ, P-SQ and H-SQ variations. Close relationships (R2 = 0.92-0.96) between load (%1RM) and bar velocity were found and they were specific for each squat variation, with faster velocities the greater the squat depth. Unlike the F-SQ and P-SQ, no sticking region was observed for the H-SQ when lifting high loads. The Pmax corresponded to a broad load range and was greatly influenced by how force output is calculated (including or excluding body mass) as well as the exact outcome variable used (MP, MPP, PP).

Movement Velocity as a Measure of Level of Effort During Resistance Exercise.

Morán-Navarro, R, Martínez-Cava, A, Sánchez-Medina, L, Mora-Rodríguez, R, González-Badillo, JJ, and Pallarés, JG. Movement velocity as a measure of level of effort during resistance exercise. J Strength Cond Res 33(6): 1496-1504, 2019-This study analyzed whether the loss of repetition velocity during a resistance exercise set was a reliable indicator of the number of repetitions left in reserve. After the assessment of one-repetition (1RM) strength and full load-velocity relationship, 30 men were divided into 3 groups according to their 1RM strength per body mass: novice, well trained, and highly trained. On 2 separate occasions and in random order, subjects performed tests of maximal number of repetitions to failure against loads of 65, 75, and 85% 1RM in 4 exercises: bench press, full squat, prone bench pull, and shoulder press. For each exercise, and regardless of the load being used, the absolute velocities associated with stopping a set before failure, leaving a certain number of repetitions (2, 4, 6, or 8) in reserve, were very similar and showed a high reliability (coefficient of variation [CV] 4.4-8.0%). No significant differences in these stopping velocities were observed for any resistance training exercise analyzed between the novice, well trained and highly trained groups. These results indicate that by monitoring repetition velocity one can estimate with high accuracy the proximity of muscle failure and, therefore, to more objectively quantify the level of effort and fatigue being incurred during resistance training. This method emerges as a substantial improvement over the use of perceived exertion to gauge the number of repetitions left in reserve.

Time course of recovery following resistance training leading or not to failure.

PURPOSE: To describe the acute and delayed time course of recovery following resistance training (RT) protocols differing in the number of repetitions (R) performed in each set (S) out of the maximum possible number (P). METHODS: Ten resistance-trained men undertook three RT protocols [S × R(P)]: (1) 3 × 5(10), (2) 6 × 5(10), and (3) 3 × 10(10) in the bench press (BP) and full squat (SQ) exercises. Selected mechanical and biochemical variables were assessed at seven time points (from - 12 h to + 72 h post-exercise). Countermovement jump height (CMJ) and movement velocity against the load that elicited a 1 m s-1 mean propulsive velocity (V1) and 75% 1RM in the BP and SQ were used as mechanical indicators of neuromuscular performance. RESULTS: Training to muscle failure in each set [3 × 10(10)], even when compared to completing the same total exercise volume [6 × 5(10)], resulted in a significantly higher acute decline of CMJ and velocity against the V1 and 75% 1RM loads in both BP and SQ. In contrast, recovery from the 3 × 5(10) and 6 × 5(10) protocols was significantly faster between 24 and 48 h post-exercise compared to 3 × 10(10). Markers of acute (ammonia, growth hormone) and delayed (creatine kinase) fatigue showed a markedly different course of recovery between protocols, suggesting that training to failure slows down recovery up to 24-48 h post-exercise. CONCLUSIONS: RT leading to failure considerably increases the time needed for the recovery of neuromuscular function and metabolic and hormonal homeostasis. Avoiding failure would allow athletes to be in a better neuromuscular condition to undertake a new training session or competition in a shorter period of time.

Validity of a single lactate measure to predict fixed lactate thresholds in athletes.

This study aimed to validate the use of a single blood lactate concentration measure taken following a 12 km h-1 running stage (BLC12) to predict and monitor fixed blood lactate concentration (FBLC) thresholds. Three complementary studies were undertaken. Study I: the relationships between BLC12 and the running speeds at FBLC of 3 mmol L-1 (S3mM) and 4 mmol L-1 (S4mM) measured during a multistage running field test were examined in 136 elite athletes. Study II: data from 30 athletes tested one year apart were used to test the predictive capacity of the equations obtained in Study I. Study III: 80 athletes were tested before and after an intensified training period to examine whether training-induced changes in FBLC thresholds could be predicted and monitored by BLC12. Study I: BLC12 was significantly (P < 0.001) and inversely related to S3mM (R2 = 0.89) and S4mM (R2 = 0.95). Study II: prediction models yielded robust correlations between the estimated and measured FBLC thresholds (r = 0.94-0.99; P < 0.001). Study III: estimated changes predicted actual training-induced changes in FBLC thresholds (r = 0.81-0.91; P < 0.001). This study gives empirical support to use a single lactate measure during a sub-maximal running field test as a simple, low-cost and practical alternative to FBLC thresholds in athletes.

Heart Rate-Based Prediction of Fixed Blood Lactate Thresholds in Professional Team-Sport Players.

The aim of this study was to investigate whether the speed associated with 90% of maximal heart rate (S90%HRmax) could predict speeds at fixed blood lactate concentrations of 3 mmol·L(-1) (S3mM) and 4 mmol·L(-1) (S4mM). Professional team-sport players of futsal (n = 10), handball (n = 16), and basketball (n = 10) performed a 4-stage discontinuous progressive running test followed, if exhaustion was not previously achieved, by an additional maximal continuous incremental running test to attain maximal heart rate (HRmax). The individual S3mM, S4mM, and S90%HRmax were determined by linear interpolation. S3mM (11.6 ± 1.5 km·h(-1)) and S4mM (12.5 ± 1.4 km·h(-1)) did not differ (p > 0.05) from S90%HRmax (12.0 ± 1.2 km·h(-1)). Very large significant (p < 0.001) relationships were found between S90%HRmax and S3mM (r = 0.82; standard error of the estimates [SEE] = 0.87 km·h(-1)), as well as between S90%HRmax and S4mM (r = 0.82; SEE = 0.87 km·h(-1)). S3mM and S4mM inversely correlated with %HRmax associated with running speeds of 10 and 12 km·h(-1) (r = 0.78-0.81; p < 0.001; SEE = 0.94-0.87 km·h(-1)). In conclusion, S3mM and S4mM can be accurately predicted by S90%HRmax in professional team-sport players.

Effects of velocity-based resistance training on young soccer players of different ages.

This study aimed to analyze the effect of velocity-based resistance training (RT) with moderate loads and few repetitions per set combined with jumps and sprints on physical performance in young soccer players of different ages. A total of 44 elite youth soccer players belonging to 3 teams participated in this study: an under-16 team (U16, n = 17) and an under-18 team (U18, n = 16) performed maximal velocity RT program for 26 weeks in addition to typical soccer training, whereas an under-21 team (U21, n = 11) did not perform RT. Before and after the training program, all players performed 20-m running sprint (T20), countermovement jump (CMJ), a progressive isoinertial loading test in squat to determine the load that elicited a ∼ 1 m · s(-1) velocity (V1LOAD) and an incremental field test to determine maximal aerobic speed (MAS). U16 showed significantly (p = 0.000) greater gains in V1LOAD than U18 and U21 (100/0/0%). Only U16 showed significantly (p = 0.01) greater gains than U21 (99/1/0%) in CMJ height. U18 obtained a likely better effect on CMJ performance than U21 (89/10/1%). The beneficial effects on T20 between groups were unclear. U16 showed a likely better effect on MAS than U21 (80/17/3%), whereas the rest of comparisons were unclear. The changes in CMJ correlated with the changes in T20 (r = -0.49) and V1LOAD (r = 0.40). In conclusion, velocity-based RT with moderate load and few repetitions per set seems to be an adequate method to improve physical performance in young soccer players.

Imposing a pause between the eccentric and concentric phases increases the reliability of isoinertial strength assessments.

This study analysed the effect of imposing a pause between the eccentric and concentric phases on the biological within-subject variation of velocity- and power-load isoinertial assessments. Seventeen resistance-trained athletes undertook a progressive loading test in the bench press (BP) and squat (SQ) exercises. Two trials at each load up to the one-repetition maximum (1RM) were performed using 2 techniques executed in random order: with (stop) and without (standard) a 2-s pause between the eccentric and concentric phases of each repetition. The stop technique resulted in a significantly lower coefficient of variation for the whole load-velocity relationship compared to the standard one, in both BP (2.9% vs. 4.1%; P = 0.02) and SQ (2.9% vs. 3.9%; P = 0.01). Test-retest intraclass correlation coefficients (ICCs) were r = 0.61-0.98 for the standard and r = 0.76-0.98 for the stop technique. Bland-Altman analysis showed that the error associated with the standard technique was 37.9% (BP) and 57.5% higher (SQ) than that associated with the stop technique. The biological within-subject variation is significantly reduced when a pause is imposed between the eccentric and concentric phases. Other relevant variables associated to the load-velocity and load-power relationships such as the contribution of the propulsive phase and the load that maximises power output remained basically unchanged.

Match-play activity profile in elite women's rugby union players.

The aim of this study was to provide an objective description of the locomotive activities and exercise intensity undergone during the course of an international-level match of female rugby union. Eight players were analyzed using global positioning system tracking technology. The total distance covered by the players during the whole match was 5,820 ± 512 m. The backs covered significantly more distance than the forwards (6,356 ± 144 vs. 5,498 ± 412 m, respectively). Over this distance, 42.7% (2,487 ± 391 m) was spent standing or walking, 35% jogging (2,037 ± 315 m), 9.7% running at low intensity (566 ± 115 m), 9.5% at medium intensity (553 ± 190 m), 1.8% at high intensity (105 ± 74 m), and 1.2% sprinting (73 ± 107 m). There were significant differences in the distance covered by forwards and backs in certain speed zones. Analysis of the relative distance traveled over successive 10-minute period of match play revealed that the greatest distances were covered during the first (725 ± 53 m) and the last (702 ± 79 m) 10-minute period of the match. The average number of sprints, the average maximum distance of sprinting, the average minimum distance of sprinting, and the average sprint distance during the game were 4.7 ± 3.9 sprints, 20.6 ± 10.5 m, 5.8 ± 0.9 -m, and 12.0 ± 3.8 m, respectively. There were substantial differences between forwards and backs. Backs covered greater total distance, distance in certain speed zones, and sprinting performance. The players spent 46.9 ± 28.9% of match time between 91 and 100% of maximum heart rate and experienced a large number of impacts (accelerometer data and expressed as g forces) during the game. These findings offer important information to design better training strategies and physical fitness testing adapted to the specific demands of female rugby union.

Blood ammonia and lactate as markers of muscle metabolites during leg press exercise.

To examine whether blood lactate and ammonia concentrations can be used to estimate the functional state of the muscle contractile machinery with regard to muscle lactate and adenosine triphosphate (ATP) levels during leg press exercise. Thirteen men (age, 34 ± 5 years; 1 repetition maximum leg press strength 199 ± 33 kg) performed either 5 sets of 10 repetitions to failure (5×10RF), or 10 sets of 5 repetitions not to failure (10×5RNF) with the same initial load (10RM) and interset rests (2 minutes) on 2 separate sessions in random order. Capillary blood samples were obtained before and during exercise and recovery. Six subjects underwent vastus lateralis muscle biopsies at rest, before the first set and after the final exercise set. The 5×10RF resulted in a significant and marked decrease in power output (37%), muscle ATP content (24%), and high levels of muscle lactate (25.0 ± 8.1 mmol·kg wet weight), blood lactate (10.3 ± 2.6 mmol·L), and blood ammonia (91.6 ± 40.5 µmol·L). During 10×5RNF no or minimal changes were observed. Significant correlations were found between: (a) blood ammonia and muscle ATP (r = -0.75), (b) changes in peak power output and blood ammonia (r = -0.87) and blood lactate (r = -0.84), and (c) blood and muscle lactate (r = 0.90). Blood lactate and ammonia concentrations can be used as extracellular markers for muscle lactate and ATP contents, respectively. The decline in mechanical power output can be used to indirectly estimate blood ammonia and lactate during leg press exercise.

Effects of two different training programs with same workload on throwing velocity by experienced water polo players.

To investigate the effects of two different strength-training programs with the same workload (impulse) on throwing velocity in water polo, 30 water polo players (M age = 17.1 yr., SD = 4.9; M mass = 71.2 kg, SD = 14.7; M height = 1.75 m, SD = 0.09 m) were randomly divided in two groups based upon throwing performance with water polo ball. The medicine-ball training group performed 3 x 6 reps with a 3-kg medicine ball, while the combination training group completed 1 x 9 repetitions with the 3-kg medicine ball, followed by 3 x 14 repetitions with a water polo ball. Both groups trained eight weeks twice per week in addition to their regular water polo training. Throwing velocity was measured with a Doppler radar gun before and after the training period. Testing included throws with a water polo ball on land and in water, as well as with 1-kg and 3-kg medicine balls on land. Statistically significant increases were found in mean peak throwing velocity with the water polo, 1-kg, and 3-kg medicine balls after training. No differences between the groups were found, except in throwing velocity with water polo on land, with a statistically significantly larger increase for the combination training group (+7.6%) than the medicine-ball training group (+3.4%). These findings indicate that after training with the same workload (impulse), increases in throwing velocity in water polo are similar and suggesting workload may be a critical variable for training results.

Toward a New Paradigm in Resistance Training by Means of Velocity Monitoring: A Critical and Challenging Narrative.

For more than a century, many concepts and several theories and principles pertaining to the goals, organization, methodology and evaluation of the effects of resistance training (RT) have been developed and discussed between coaches and scientists. This cumulative body of knowledge and practices has contributed substantially to the evolution of RT methodology. However, a detailed and rigorous examination of the existing literature reveals many inconsistencies that, unless resolved, could seriously hinder further progress in our field. The purpose of this review is to constructively expose, analyze and discuss a set of anomalies present in the current RT methodology, including: (a) the often inappropriate and misleading terminology used, (b) the need to clarify the aims of RT, (c) the very concept of maximal strength, (d) the control and monitoring of the resistance exercise dose, (e) the existing programming models and (f) the evaluation of training effects. A thorough and unbiased examination of these deficiencies could well lead to the adoption of a revised paradigm for RT. This new paradigm must guarantee a precise knowledge of the loads being applied, the effort they involve and their effects. To the best of our knowledge, currently this can only be achieved by monitoring repetition velocity during training. The main contribution of a velocity-based RT approach is that it provides the necessary information to know the actual training loads that induce a specific effect in each athlete. The correct adoption of this revised paradigm will provide coaches and strength and conditioning professionals with accurate and objective information concerning the applied load (relative load, level of effort and training effect). This knowledge is essential to make rational and informed decisions and to improve the training methodology itself.

Muscle strength and golf performance: a critical review.

Golf has become an increasingly popular sport and a growing body of research trying to identify its main physical requirements is being published. The aim of this review was twofold: first, to examine the existing scientific literature regarding strength training and golf in healthy, non-injured, subjects; and second, to reach conclusions that could provide information on how to design more effective strength training programs to improve golf performance as well as directions for future research. Studies which analyzed the relationship between muscle strength, swing performance variables (club head speed, driving distance, ball speed) and skill (handicap, score) were reviewed. Changes in swing performance following different strength training programs were also investigated. Finally, a critical analysis about the methodologies used was carried out. The results of the reviewed studies seem to indicate that: 1) a positive relationship exists between handicap and swing performance (even though few studies have investigated this issue); 2) there is a positive correlation between skill (handicap and/or score) and muscle strength; and 3) there is a relationship between driving distance, swing speed, ball speed and muscle strength. Results suggest that training leg-hip and trunk power as well as grip strength is especially relevant for golf performance improvement. Studies that analyzed variations in swing performance following resistance-only training programs are scarce, thus it is difficult to prove whether the observed improvements are attributable to changes in strength levels. Many of the studies reviewed presented some methodological errors in their design and not all strength assessment protocols seemed appropriate. Further studies should determine muscle strength needs in relation to final swing performance, using well designed experiments and strict isoinertial assessment protocols which adequately relate to specific golf motion, age and skill level. More studies with elite participants, either professional or amateur, would be especially desirable. Key pointsPOSITIVE CORRELATIONS EXIST BETWEEN: 1) handicap and swing performance variables; 2) muscle strength and skill (handicap and/or golf score); and 3) driving dis-tance, swing speed, ball speed and muscle strength.Leg-hip, trunk power and grip strength seem espe-cially relevant for golf performance improvement.Further research should determine muscle strength needs in relation to final swing performance, using well designed experiments and strict assessment pro-tocols which adequately relate to specific golf mo-tion, age and skill level.