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This study aimed to compare the accuracy of the power output, measured by a power meter, with respect to the speed, measured by an inertial measurement unit (IMU) and a global navigation satellite system (GNSS) sport watch to determine the critical power (CP) and speed (CS), work over CP (W') and CS (D'), and long‐duration performance (i.e., 60 min). Fifteen highly trained athletes randomly performed seven time trials on a 400 m track. The CP/CS and W'/D' were defined through the inverse of time model using the 3, 4, 5, 10, and 20 min trials. The 60 min performance was estimated through the power law model using the 1, 3, and 10 min trials and compared with the actual performance. A lower standard error of the estimate was obtained when using the power meter (CP: 2.7 [2.1–3.3] % and W': 13.8 [10.4–17.3] %) compared to the speed reported by the IMU (CS: 3.4 [2.5–4.3] %) and D': 20.7 [16.6–24.7] %) and GNSS sport watch (CS: 3.4 [2.5–4.3] % and D': 20.6 [16.7–24.7] %). A lower coefficient of variation was also observed for the power meter (4.9 [3.7–6.1] %) Regarding the speed reported by the IMU (10.9 [7.1–14.8] %) and GNSS sport watch (10.9 [7.0–14.7] %) in the 60 min performance estimation, the power meter offered lower errors than the IMU and GNSS sport watch for modelling endurance performance on the track. Highlights: Recent advances in wearable technology are creating new opportunities to accurately monitor running intensity in contexts where precision is essential (i.e., track running) for athletes' (e.g., pacing) and coaches' (e.g., performance analysis) tasks.The track mode of recent global navigation satellite system (GNSS) sport watches seems to offer a decent improvement. Alternatively, new inertial measurement units (IMUs) designed specifically for running have emerged offering the capability to monitor distance in specific contexts such as treadmills and indoor tracks. Additionally, these IMUs provide new metrics of the external load.The power meter provided by the Stryd inertial measurement unit (IMU) demonstrated lower estimation errors in modelling endurance running performance on the track compared to speed data reported by the same IMU and a Garmin GNSS sports watch (using the track mode). [ABSTRACT FROM AUTHOR]

This study aimed to explore the effect of the menstrual cycle (MC) phases (i.e., early follicular phase [EFP], late follicular phase [LFP], and mid-luteal phase [MLP]) on the repetitions performed to momentary failure in back squat and bench press exercises, as well as to determine subsequent fatigue (i.e., change in countermovement jump [CMJ], perceived effort, and muscle soreness). Twelve physically active eumenorrheic women performed a back squat and bench press set to momentary failure at 80% of the one-repetition maximum during the EFP, LFP, and MLP. The results revealed that subjects were able to perform 2.2 [0.2 to 4.2] more repetitions in the LFP with respect to the EFP for the back squat exercise (p = 0.009), but no significant differences were observed for the bench press (p = 0.354). The EFP displayed a larger CMJ height drop (−0.86 [−1.71 to −0.01] cm) with respect to the LFP (0.01 [−0.57 to 0.58] cm) and the MLP (−0.36 [−1.15 to 0.43] cm). Neither the perceived effort of each set to failure nor the resulting muscle soreness differed between MC phases. Therefore, practitioners should be aware that the MC could condition the repetitions available to momentary failure and the resulting allostatic load. [ABSTRACT FROM AUTHOR]

This study aimed to determine the validity and between-day reliability of the mean velocity (MV), peak velocity (PV), mean power (MP), and peak power (PP) provided by the Vitruve linear position transducer at different submaximal loads in the free-weight and Smith machine back squat using GymAware as a reference point. Fourteen male sports science students (free-weight back squat one-repetition maximum [1RM]: 132.5 ± 28.5 kg, Smith machine back squat 1RM: 163.9 ± 30.4 kg) performed six experimental sessions, twice per week with 72 hours of rest. The first two included the assessment of the 1RM of both exercises. In the four remaining, both linear position transducers were simultaneously used to record MV, PV, MP, PP of each repetition during an incremental load test (i.e., 20, 40, 60, 80, 90% 1RM) with three minutes of rest between sets. Vitruve displayed both fixed and proportional bias for certain relative loads across all variables. Vitruve did not meet the validity criteria for all (MV, PP) or at least two (MP, PV) relative loads (Coefficient of variation [CV] > 10%; Pearson correlation < 0.70; Effect size > 0.60). MV, PV, MP, and PP recorded by Vitruve displayed acceptable reliability (CV < 10%) with superior reliability observed during a Smith Machine compared to free-weight back squat, and for velocity compared to power variables. Considering GymAware as a reference point, Vitruve was not valid for measuring velocity and power outcomes. Acceptable validity was observed only for PV in the Smith machine back squat, while the other variables—regardless of relative loads and exercise modes—were mostly inaccurate. All variables demonstrated acceptable reliability, with greater reliability noted in the Smith machine compared to the free-weight back squat exercise mode. [ABSTRACT FROM AUTHOR]

This study aims to determine the variability of the components of fitness along the menstrual cycle (MC) of physically active eumenorrheic women. Fifteen subjects were monitored along two consecutive MCs through the calendar-based counting method in combination with a urine luteinizing hormone surge kit. Subjects were tested at the early follicular phase (EFP), pre-ovulatory or late follicular phase (LFP), and post-ovulatory or mid-luteal phase (MLP). In each session, the back squat one-repetition maximum (1-RM), maximum fat oxidation (MFO), maximum oxygen uptake (VO2max) and acute recovery capacity were determined. The results revealed a wide variability among components of fitness and a low to high variability among subjects (acute recovery: 3.6% [range 1.5 to 9.5%]; back squat 1-RM: 6.1% [range 2.2 to 11%]; VO2max : 6.6% [range 1.1 to 15%]; MFO: 23% [range 4.6 to 35%]). Despite the individual nature, considering the number and magnitude of the responses in each MC phase, VO2max and acute recovery capacity tended to be enhanced at the LFP, the MFO at the MLP, and the back squat 1-RM remained stable along the MC. Thus, practitioners are aware of which components are susceptible to change along the MC phase, but an individual monitoring is recommended. [ABSTRACT FROM AUTHOR]

This study aimed to determine the influence of the testing environment (track vs. treadmill), time trial order (long-short vs. short-long), and timing (within-session vs. between-sessions) on the critical power (CP) and work over CP (W´), using the power metric in runners. Fifteen highly trained athletes performed three test sessions composed of two time trials of 9- and 3-min, separated by a 30-min rest period. One session was performed on a track, and two sessions on a treadmill, alternating the order of the time trials. The CP and W´ values determined on the track were significantly greater and lower than on the treadmill, respectively (p<0.001; CP≥89 W; W´≥3.7 kJ). Their degree of agreement was low (SEE CP>5%; W´>10%) and therefore was not interchangeable. There were no performance differences in the timing of the time trials (p=0.320). Lastly, performing the 9-min trial first resulted in a greater power output compared to when executed last (p<0.001; 4.9 W), although this resulted in similar CP and W´ values (Bias<5 and 10%, respectively). In conclusion, it is feasible to test CP and W´ in a single testing session, irrespective of the time trial order, although not interchangeably between track and treadmill. [ABSTRACT FROM AUTHOR]

This study aimed to compare the acute effect of four back squat velocity-based training (VBT) protocols in terms of intensity (60% vs. 80% of the one repetition maximum [1RM]) and volume (10% vs. 30% threshold for velocity loss in the set) on the maximal aerobic speed (MAS) estimated from a running track test (RTT) in recreationally trained young adult men and women. Twenty participants (eleven men and nine women) undertook five randomized protocols in separate occasions: (i) RTT alone (control condition); (ii) VBT with 60% 1RM and a 10% velocity loss followed by RTT (VBT60–10 + RTT); (iii) VBT with 60% 1RM and a 30% velocity loss followed by RTT (VBT60–30 + RTT); (iv) VBT with 80% 1RM and 10% velocity loss followed by RTT (VBT80–10 + RTT); (v) VBT with 80% 1RM and 30% velocity loss followed by RTT (VBT80–30 + RTT). All VBT protocols involved three sets with three minutes of rest. The MAS was higher for RTT (control) than VBT60–30 + RTT (p < 0.001; Δ = 3.8%), VBT60–10 + RTT (p = 0.006; Δ = 2.8%), VBT80–10 + RTT (p = 0.008; Δ = 2.7%), and VBT80–30 + RTT (p = 0.019; Δ = 1.9%). No protocol × sex interaction was noted (p = 0.422). Therefore, regardless of sex, MAS is acutely impaired after VBT, especially if the training sets are performed with a low relative load and a high velocity loss threshold. [ABSTRACT FROM AUTHOR]

Purpose: The critical power (CP) concept has been extended from cycling to the running field with the development of wearable monitoring tools. Particularly, the Stryd running power meter and its 9/3-minute CP test is very popular in the running community. Locating this mechanical threshold according to the physiological landmarks would help to define each boundary and intensity domain in the running field. Thus, this study aimed to determine the CP location concerning anaerobic threshold, respiratory compensation point (RCP), and maximum oxygen uptake (VO2max). Method: A group of 15 high-caliber athletes performed the 9/3-minute Stryd CP test and a graded exercise test in 2 different testing sessions. Results: Anaerobic threshold, RCP, and CP were located at 73% (5.41%), 86.82% (3.85%), and 88.71% (5.84%) of VO2max, respectively, with a VO2max of 66.3 (7.20) mL/kg/min. No significant differences were obtained between CP and RCP in any of its units (ie, in watts per kilogram and milliliters per kilogram per minute; P ≥.184). Conclusions: CP and RCP represent the same boundary in high-caliber athletes. These results suggest that coaches and athletes can determine the metabolic perturbance threshold that CP and RCP represent in an easy and accessible way. [ABSTRACT FROM AUTHOR]

Ruiz-Alias, SA, Nncupil-Andrade, AA, Pe' rez-Castilla, A, and Garc'ıa-Pinillos, F. Can we predict long-duration running power output? Validity of the critical power, power law, and logarithmic models. J Strength Cond Res 38(2): 306-310, 2024--Predicting long-distance running performance has always been a challenge for athletes and practitioners. To ease this task, different empirical models have been proposed to model the drop of the running work rate with the increase of time. Therefore, this study aims to determine the validity of different models (i.e., CP, power law, and Peronnet) to predict long-duration running power output (i.e., 30 and 60 minutes). In a 4-week training period, 15 highly trained athletes performed 7-time trials (i.e., 3, 4, 5, 10, 20, 30, and 60 minutes) in a randomized order. Then, their power-duration curves (PDCs) were defined through the work-time critical power model (CPwork), power-1/time (CP1/time), 2-parameter hyperbolic (CP2hyp), 3-parameter hyperbolic (CP3hyp), the undisclosed Stryd (CPstryd), and Golden Cheetah (CPcheetah) proprietary models, and the power law and Peronnet models using the 3 to 20 minutes time trials. These ones were extrapolated to the 30- and 60-minute power output and compared with the actual performance. The CP2hyp, CP3hyp, CPstryd, and CPcheetah provided valid 30- and 60-minute power output estimations (#2.6%). The CPwork and CP1/time presented a large predicting error for 30 minutes ($4.4%), which increased for 60 minutes ($8.1%). The power law and Peronnet models progressively increased their predicting error at the longest duration (30 minutes: #21.6%; 60 minutes: #2 6.6%), which was conditioned by the endurance capability of the athletes. Therefore, athletes and practitioners are encouraged to applicate the aforementioned valid models to their PDC to estimate the 30-minute and 60-minute power output. [ABSTRACT FROM AUTHOR]

The aims of this study were (i) to estimate the functional threshold power (FTP) and critical power (CP) from single shorter time trials (TTs) (i. e. 10, 20 and 30 minutes) and (ii) to assess their location in the power-duration curve. Fifteen highly trained athletes randomly performed ten TTs (i. e. 1, 2, 3, 4, 5, 10, 20, 30, 50 and 60 minutes). FTP was determined as the mean power output developed in the 60-min TT, while CP was estimated in the running power meter platform according to the manufacturer's recommendations. The linear regression analysis revealed an acceptable FTP estimate for the 10, 20 and 30-min TTs (SEE≤12.27 W) corresponding to a correction factor of 85, 90 and 95%, respectively. An acceptable CP estimate was only observed for the 20-min TT (SEE=6.67 W) corresponding to a correction factor of 95%. The CP was located at the 30-min power output (1.0 [–5.1 to 7.1] W), which was over FTP (14 [7.0 to 21] W). Therefore, athletes and practitioners concerned with determining FTP and CP through a feasible testing protocol are encouraged to perform a 20-min TT and apply a correction factor of 90 and 95%, respectively. [ABSTRACT FROM AUTHOR]

This study aimed to explore the acute effect of 4 velocity-based resistance training (VBT) protocols on 2000-m rowing ergometer (RE2000) time trial, as well as the behavior of the maximal neuromuscular capacities when RE2000 is performed alone or preceded by VBT protocols in the same session. Fifteen male competitive rowers (15-22 years) undertook 5 randomized protocols in separate occasions: (a) RE2000 alone (control condition); (b) VBT against 60% of 1 repetitionmaximum (1RM) with a velocity loss in the set of 10% followed by RE2000 (VBT60-10 + RE2000); (c) VBT against 60% 1RM with a velocity loss in the set of 30% followed by RE2000 (VBT60-30 + RE2000); (d) VBT against 80% 1RM with a velocity loss in the set of 10% followed by RE2000 (VBT80-10 + RE2000); (e) VBT against 80% 1RM with a velocity loss in the set of 30% followed by RE2000 (VBT80-30+ RE2000). The load-velocity relationship (load-axis intercept [L0], velocity-axis intercept [v0], and area under the load-velocity relationship line [Aline]) was used to evaluate the maximal neuromuscular capacities during the prone bench pull exercise before and after each protocol. The time trial was significantly longer for VBT60-30 + RE2000 and VBT80-30 + RE2000 than for RE2000, VBT60-10 + RE2000 and VBT80-10 + RE2000 (all p, 0.001; ES 5 0.10-0.15). L0 and Aline were significantly reduced after all protocols (p, 0.001; ES 5 0.10-0.13), with Aline reduction more accentuated for VBT60-10 + RE2000, VBT60-30 + RE2000, VBT80-30 + RE2000, and RE2000 (all p 5 0.001; ES 5 0.11-0.18) than for VBT80-10 + RE2000 (p 5 0.065; ES 5 0.05). Therefore, VBT protocols with greater velocity loss in the set (30% vs. 10%) negatively affected subsequent rowing ergometer performance, in line with impairment in Aline pulling performance. [ABSTRACT FROM AUTHOR]

This study aims to compare the effect of the Nike ZoomX Dragonfly track spikes and the Nike ZoomX VaporflyNext% 2 marathon shoes on the fatigue manifestations present over and after a long-distance track training session. Thirteen highly trained athletes completed two training sessions (i. e., 9- and 3-minute time trials with complete recovery) with the aforementioned footwear models. The pace, ground contact time, and stride length were measured over the time trials, and maximal countermovement jumps were performed previously and after the training session. The results revealed that, although there was no significant interaction in the pace distribution (p≥0.072), athletes tend to be only able to increase the pace at the last lap with the marathon shoes (5.4 meters [−3.7 to 14.5 meters]) meanwhile with the track spikes it further decreased (−3.1 meters [−9.8 to 3.6 meters]). A reduced ground contact time over the session (p=0.025) and a tendency toward increasing stride length (p=0.09) in the last time trial were observed. The significant interaction on the countermovement jump height (p=0.023; Track spikes: −5.60%; Marathon shoes: 0.61%) also indicates that footwear influences the resulted allostatic load. [ABSTRACT FROM AUTHOR]

Ruiz-Alias, SA, Pe' rez-Castilla, A, Soto-Hermoso, VM, and Garc'ıa-Pinillos, F. Influence of the world athletics stack height regulation on track running performance. J Strength Cond Res 37(11): 2260-2266, 2023--A new footwear regulation based on limiting the stack height (i.e., amount of material between the feet and the ground) has been established byWorld Athletics to ensure that performance is achieved through the primacy of human effort over technology in running shoes. Analyzing the effect of legal and illegal shoes on running performance is therefore needed to determine its effectiveness. Thus, this study aimed (a) to compare the effect of 2 footwear models categorized as legal and illegal by the World Athletics regulation on track running performance and (b) to analyze the derived metrics of the athletes' biomechanics when using each footwear model at racing paces. Within 1 week, 14 highly trained athletes performed 2 testing sessions composed of 2 time trials of 9- and 3-minute duration with 30 minutes of recovery between them. The athletes wore the "Nike ZoomX Dragonfly" track spikes model and the "Nike ZoomX Vaporfly Next % 2" marathon shoe model in a counterbalanced randomized order. The results revealed that (a) there was only a small worthwhile improvement in the 3-minute time trial when using themarathon shoes of 0.97%(20.04 to 1.98%) and (b) there was amain effect of footwear in 7 of the 9 biomechanical variables analyzed (p # 0.050). The ground contact time was the unique performance predictor (p 5 0.005, adjusted R2 5 0.476). Altogether, the use of legal and illegal running shoes altered the runners form, which only influenced the mid-distance performance. [ABSTRACT FROM AUTHOR]

This study aimed to examine the effects of altering the intra-session exercise sequence of a concurrent training program on the load–velocity relationship variables obtained from different compound exercises. Physically active subjects (n = 24, age = ∼21 years) were assigned to one group that performed sprint interval training (sprints: 4–6; intensity: all-out; duration: 30 s; rest: 4 min) followed by resistance training (exercises: back squat and bench press; sets per exercise: 4–6; load: 60–80% of the one-repetition maximum; repetition in reserve: 6–1; rest: 2 min) (SIT + RT) or another group that performed the opposite sequence (RT + SIT). Exercises modes were separated by 10 min. Both groups trained three times per week over an eight-week period. The individualized load–velocity relationships were assessed before and after training through an incremental loading test during the back squat and bench press exercises and three variables were subsequently calculated: load-axis intercept (L 0), velocity-axis intercept (v 0), and area under the line (Aline = L 0⋅ v 0/2). Regardless of exercise sequence, both groups increased L 0 (ES range = 0.78–0.91) and Aline (ES range = 0.50–0.55) but decreased v 0 (ES range = −0.36 to −0.46) during the back squat exercise, while all load–velocity relationship variables were increased (ES range = 0.04–2.20) during the bench press exercise. The SIT + RT group showed a moderately greater bench press v 0 increase compared to the RT + SIT group (ES = −1.07). These results indicate that both intra-session exercise sequences can induce comparable improvements in the load–velocity relationship variables after an eight-week concurrent training program. [ABSTRACT FROM AUTHOR]

This study aimed to explore the acute effect of 2 high-intensity running protocols (high-intensity interval training [HIIT] and sprint interval training [SIT]) on resistance training (RT) performance and their combined effect on the lower-body maximal neuromuscular capacities. Eighteen healthy subjects randomly completed 3 experimental protocols: only RT, HIIT + RT, and SIT + RT. Characteristics of the RT protocol include 3 back-squat sets of 10 repetitions or 20% velocity loss against 60% of 1 repetition maximum with 3 minutes of interset rest. Characteristics of the high-intensity running protocols include HIIT (4 intervals of 4 minutes at -110% of functional threshold power with 3 minutes of interinterval rest) and SIT (6 all-out sprints of 30 seconds with 4 minutes and 24 seconds of interinterval rest). The force-velocity relationship (maximal values of force [F0], velocity [v0], and power [Pmax]) was evaluated at the beginning and at the end of each experimental protocol. The number of back-squat repetitions (p = 0.006; effect size [ES] = -0.96), fastest velocity (p = 0.003; ES = -0.63), and average velocity (p = 0.001; ES = -0.73) were lower for the SIT + RT protocol compared with the RT protocol, but no significant differences were observed between the RT and HIIT + RT (p ≥T0.057; ES ≤.-0.46, except -0.82 for the number of back-squat repetitions) and HIIT + RT and SIT + RT (p ≥T0.091; ES .0-0.35) protocols. The 3 protocols induced comparable decreases in v0 and Pmax (F(2,34) 2,0.96; p ≥ 0.393), but F0 tended to decrease after the SIT + RT protocol and to increase after the RT and HIIT + RT protocols (F(2,34) = 4.37; p = 0.035). Compared with RT alone, the data suggest that SIT deteriorates RT quality and F0 capacity more than long-interval HIIT. [ABSTRACT FROM AUTHOR]

This systematic review aims to synthesise the effects of current shoe models in each shoe category and their specific features on running economy, performance and biomechanics. Electronic databases such as Web of Science, SPORTDiscuss, PubMed and Scopus were used to identify studies from 2015 to date. Due to the existing lack of consensus to define running shoes, only studies that specified the shoe brand and models used to assess their effect over runners with a certain level of fitness and training routine were included. Quality assessment of cross-sectional and intervention studies was conducted by three independent raters using a modified version of the Quality Index and the PEDro scale, respectively. A total of 36 articles were finally included, involving the analysis of 61 different shoe models over 10 different topics (i.e., running economy, running performance, spatiotemporal parameters, ground reaction forces, joint stiffness, achilles tendon, plantar pressure, tibiofemoral load, foot strike pattern and joint coordination). With this review, runners and practitioners in the field that are concerned about selecting a suitable shoe for performance, training, or injury prevention functionality have clear information about the effects of the current shoe models and their specific features. [ABSTRACT FROM AUTHOR]