The purpose of this study was to analyze multiple effects of an extended interval training (EIT) protocol on countermovement jump (CMJ) and handgrip strength in endurance athletes and to determine the relationship between fatigue and potentiation. Thirty experienced sub-elite male long-distance runners (age = 28.26 ± 8.27 years, body mass index = 22.24 ± 2.50 kg·m, and (Equation is included in full-text article.)= 58.7 ± 4.50 ml·kg·min) participated voluntarily in this study. Subjects performed the protocol on an outdoor running track, which consisted of 12 runs of 400 m, grouped into 4 sets of 3 runs, with a passive recovery of 1 minute between runs and 3 minutes between sets (4 × 3 × 400 m). During protocol, fatigue parameters (lactate, heart rate, and rate of perceived exertion) and performance parameters (CMJ, handgrip strength, and time spent in each 400-m run) were controlled. Analysis of variance revealed a significant improvement in CMJ (p < 0.001) throughout the protocol. Cluster analysis grouped according to whether potentiation was experienced (responders group, n = 17) or not (nonresponders group, n = 13) in relation to CMJ change from rest to fatigued condition at the end of activity. Responders group significantly improved (p ≤ 0.05) the performance in CMJ, handgrip strength and time spent in each 400-m run. Results suggest that despite induced fatigue for EIT, trained subjects can maintain their strength and power levels and their work capacity. This fact would support the rationale that improvements in performance may be due not only to metabolic adaptations but also to specific neuromuscular adaptations. Therefore, the evaluation of power should be considered simultaneously with running performance when monitoring endurance athletes.

This study aimed to evaluate the concurrent validity of two different inertial measurement units for measuring spatiotemporal parameters during running on a treadmill, by comparing data with a high-speed video analysis (VA) at 1,000 Hz. Forty-nine endurance runners performed a running protocol on a treadmill at comfortable velocity (i.e., 3.25 ± 0.36 m.s-1). Those wearable devices (i.e., Stryd™ and RunScribe™ systems) were compared to a high-speed VA, as a reference system for measuring spatiotemporal parameters (i.e. contact time [CT], flight time [FT], step frequency [SF] and step length [SL]) during running at comfortable velocity. The pairwise comparison revealed that the Stryd™ system underestimated CT (5.2%, p < 0.001) and overestimated FT (15.1%, p < 0.001) compared to the VA; whereas the RunScribe™ system underestimated CT (2.3%, p = 0.009). No significant differences were observed in SF and SL between the wearable devices and VA. The intra class correlation coefficient (ICC) revealed an almost perfect association between both systems and high-speed VA (ICC > 0.81). The Bland-Altman plots revealed heteroscedasticity of error (r2 = 0.166) for the CT from the Stryd™ system, whereas no heteroscedasticity of error (r2 < 0.1) was revealed in the rest of parameters. In conclusion, the results obtained suggest that both foot pods are valid tools for measuring spatiotemporal parameters during running on a treadmill at comfortable velocity. If the limits of agreement of both systems are considered in respect to high-speed VA, the RunScribe™ seems to be a more accurate system for measuring temporal parameters and SL than the Stryd™ system.

The results showed that GS is an important predictor of functional capacity (physical and cognitive function) in adults over 65 years old.

PurposeThe purpose of this study was to determine the effects of 12 weeks of barefoot running on foot strike patterns, inversion–eversion and foot rotation in long-distance runners.MethodsThirty-one endurance runners with no experience in barefoot running were randomized into a control group and an experimental group who received barefoot training. At pre-test and post-test, all subjects ran at low and high self-selected speeds on a treadmill. Data were collected by systematic observation of lateral and back recordings at 240 Hz.ResultsMcNemar's test indicated significant changes (p < 0.05) in the experimental group at both high and low speed running in foot strike patterns, reducing the percentage of high rearfoot strikers and increasing the number of midfoot strikers. A significant increase (p < 0.05) of external rotation of the foot and a decrease of inversion occurred at comfortable speed in the experimental group.ConclusionTwelve weeks of barefoot running, applied progressively, causes significant changes in foot strike pattern with a tendency toward midfoot or forefoot strikes, regardless of running speed and significant changes in foot rotation at low speed, while the inversion was reduced in left foot at low speed with a tendency toward centered strike.

García-Pinillos, F, Cámara-Pérez, JC, Soto-Hermoso, VM, and Latorre-Román, PÁ. A High Intensity Interval Training (HIIT)-based running plan improves athletic performance by improving muscle power. J Strength Cond Res 31(1): 146-153, 2017-This study aimed to examine the effect of a 5-week high-intensity intermittent training (HIIT)-based running plan on athletic performance and to compare the physiological and neuromuscular responses during a sprint-distance triathlon before and after the HIIT period. Thirteen triathletes were matched into 2 groups: the experimental group (EG) and the control group (CG). The CG was asked to maintain their normal training routines, whereas the EG maintained only their swimming and cycling routines and modified their running routine. Participants completed a sprint-distance triathlon before (pretest) and after (posttest) the intervention period. In both pretest and posttest, the participants performed 4 jumping tests: before the race (baseline), postswim, postcycling, and postrun. Additionally, heart rate was monitored (HRmean), whereas rate of perceived exertion (RPE) and blood lactate accumulation (BLa) were registered after the race. No significant differences (p ≥ 0.05) between groups were found before HIIT intervention (at pretest). Significant group-by-training interactions were found in vertical jumping ability and athletic performance: the EG improved jumping performance (∼6-9%, p ≤ 0.05, effect size (ES) > 0.7), swimming performance (p = 0.013, ES = 0.438), and running time (p = 0.001, ES = 0.667) during the competition, whereas the CG remained unchanged (p ≥ 0.05, ES < 0.4). No changes (p ≥ 0.05, ES < 0.4) were observed in RPE, HRmean, and BLa. A linear regression analysis showed that ΔCMJ predicted both the ΔRu_time (R = 0.559; p = 0.008) and the ΔOverall_time (R = 0.391; p = 0.048). This low-volume, HIIT-based running plan combined with the high training volumes of these triathletes in swimming and cycling improved athletic performance during a sprint-distance triathlon. This improvement may be due to improved neuromuscular characteristics that were transferred into improved muscle power and work economy.

The aim of this study was to determine the influence of barefoot running on foot-strike patterns, eversion-inversion, running speed and vertical foot rotation in endurance runners. Eighty healthy recreational runners (age = 34.11 ± 12.95 years old, body mass index = 22.56 ± 2.65 kg · m(-2)) performed trials in shod/unshod running conditions on a treadmill at comfortable and competitive self-selected speeds. Data were collected by systematic observation of lateral and back recordings at 240 Hz. McNemar's test indicated significant differences between shod/unshod conditions and foot strike at comfortable and competitive speeds (P < 0.001). Speed was related to vertical foot rotation type for shod (P < 0.01) and unshod conditions (P < 0.05). Significant differences were found between shod/unshod conditions in foot rotation at comfortable running speeds (P < 0.001) and competitive running speeds (P < 0.01). No significant difference was found in inversion or eversion (P ≥ 0.05). In conclusion, the results suggest that running kinematics, in terms of foot-strike patterns and vertical foot rotation, differ between shod/unshod conditions, while the inversion or eversion degree remains unchanged.

Roche-Seruendo, LE, García-Pinillos, F, Haicaguerre, J, Bataller-Cervero, AV, Soto-Hermoso, VM, and Latorre-Román, PÁ. Lack of influence of muscular performance parameters on spatiotemporal adaptations with increased running velocity. J Strength Cond Res 32(2): 409-415, 2018-This study aimed to analyze the influence of muscular performance parameters on spatiotemporal gait characteristics during running when gradually increasing speed. Fifty-one recreationally trained male endurance runners (age, 28 ± 8 years) voluntarily participated in this study. Subjects performed a battery of jumping tests (squat jump, countermovement jump, and 20-cm drop jump), and after that, the subjects performed an incremental running test (10-20 km·h) on a motorized treadmill. Spatiotemporal parameters were measured using the OptoGait system. Cluster k-means analysis grouped subjects according to the jumping test performance, by obtaining a group of good jumpers (n = 19) and a group of bad jumpers (n = 32). With increased running velocity, contact time was shorter and flight time and step length were longer, whereas cadence and stride angle were greater (p < 0.001). No significant differences between groups (p ≥ 0.05) were found at any running speed. The results obtained indicate that increased running velocity produced no differences in spatiotemporal adaptations between those runners with good jumping ability and those with poor jumping ability. Based on that, it seems that muscular performance parameters do not play a key role in spatiotemporal adaptations experienced by recreational endurance runners with increased velocity. However, taken into consideration the well-known relationship between running performance and neuromuscular performance, the authors suggest that muscular performance parameters would be much more determinant in the presence of fatigue (exhausted condition) or in the case of considering other variables such as running economy or kinetic.

PurposeThis study aimed to describe the acute effects of 2 different high-intensity intermittent trainings (HIITs) on postural control, countermovement jump (CMJ), squat jump (SJ), and stretch-shortening cycle (SSC) utilisation, and to compare the changes induced by both protocols in those variables in endurance runners.MethodsEighteen recreationally trained endurance runners participated in this study and were tested on 2 occasions: 10 runs of 400 m with 90 s recovery between running bouts (10 × 400 m), and 40 runs of 100 m with 30 s recovery between runs (40 × 100 m). Heart rate was monitored during both HIITs; blood lactate accumulation and rate of perceived exertion were recorded after both protocols. Vertical jump ability (CMJ and SJ) and SSC together with postural control were also controlled during both HIITs.ResultsRepeated measures analysis revealed a significant improvement in CMJ and SJ during 10 × 400 m (p < 0.05), whilst no significant changes were observed during 40 × 100 m. Indexes related to SSC did not experience significant changes during any of the protocols. As for postural control, no significant changes were observed in the 40 × 100 m protocol, whilst significant impairments were observed during the 10 × 400 m protocol (p < 0.05).ConclusionA protocol with a higher number of shorter runs (40 × 100 m) induced different changes in those neuromuscular parameters than those with fewer and longer runs (10 × 400 m). Whereas the 40 × 100 m protocol did not cause any significant changes in vertical jump ability, postural control or SSC utilisation, the 10 × 400 m protocol impaired postural control and caused improvements in vertical jumping tests.