Running Pace Research Articles

Changes in Serum Iron and Leukocyte mRNA Levels of Genes Involved in Iron Metabolism in Amateur Marathon Runners-Effect of the Running Pace.

Iron is essential for physical activity due to its role in energy production pathways and oxygen transportation via hemoglobin and myoglobin. Changes in iron-related biochemical parameters after physical exercise in athletes are of substantial research interest, but molecular mechanisms such as gene expression are still rarely tested in sports. In this paper, we evaluated the mRNA levels of genes related to iron metabolism (PCBP1, PCBP2, FTL, FTH, and TFRC) in leukocytes of 24 amateur runners at four time points: before, immediately after, 3 h after, and 24 h after a marathon. We measured blood morphology as well as serum concentrations of iron, ferritin, and C-reactive protein (CRP). Our results showed significant changes in gene expression (except for TFRC), serum iron, CRP, and morphology after the marathon. However, the alterations in mRNA and protein levels occurred at different time points (immediately and 3 h post-run, respectively). The levels of circulating ferritin remained stable, whereas the number of transcripts in leukocytes differed significantly. We also showed that running pace might influence mRNA expression. Our results indicated that changes in the mRNA of genes involved in iron metabolism occurred independently of serum iron and ferritin concentrations.

Altered Lower Extremity Joint Work Profiles During Inclined Running At Iso-efficiency Speeds

Inclined running is a common component of many runners’ training programs in the form of hill repeats. Runners are often forced to slow their running pace, iso-efficiency speed (ISO), during inclined running to maintain their metabolic effort. Though commonly used in training, little is known regarding the changes in joint kinetics associated with running on an inclined treadmill at an ISO speed. PURPOSE: To evaluate changes in lower extremity joint work when running on increasing inclines at ISO speeds. METHODS: Eleven NCAA Division I runners performed five 5-second treadmill running trials during each of three ISO speed inclined conditions: 0% incline, 4% incline, and 8% incline. ISO speed was confirmed using oxygen consumption (VO2) using indirect calorimetry. Kinematics and ground reaction forces were recorded simultaneously using an 8-camera motion capture system (100 Hz, Qualisys Inc.) and instrumented treadmill (1000 Hz, Bertec), respectively. Visual 3D was used to calculate ankle, knee and hip joint powers while custom software (MATLAB, MathWorks) calculated positive and negative joint work as joint power integrated with time. A repeated measures ANOVA with Tukey’s post-hoc was used to determine the effect of treadmill incline on joint work. RESULTS: Negative ankle joint work increased while negative knee and hip joint work decreased with increasing treadmill incline (Table 1). Positive ankle and hip joint work increased while positive knee work decreased with increasing treadmill incline (Table 1). CONCLUSIONS: Our findings suggest that even at ISO speeds (i.e., reduced speeds to maintain effort), inclined treadmill running increases eccentric demands on plantarflexors, and concentric demands on knee and hip extensors. These data may support altered training prescriptions for athletes recovering from joint-specific muscular injuries to minimize training-related stresses placed on those tissues.

Comparison of Running Power to Metabolic Cost at Various Submaximal Running Speeds and Inclinations

Running pace is one of the primary measures of running intensity, however, variations in grade limit quantifying intensity solely based on pace. With the advent of wearable running power meters, runners can address the external work stimulus inclusive of pace and grade. PURPOSE: The purpose was to compare running power measured by a Running Power Meter to the metabolic cost of running at different speeds and inclinations. METHODS: 5 collegiate cross country runners (male n=2, age=21±1.414 yrs, weight=69.8±3.960 kg, height=180±4.243 cm; female n=3, age=19.67±0.577 yrs, weight=54.07±2.290 kg, height=164.33±10.263 cm) participated in 10 trials of submaximal running at different speeds and inclinations. Subjects first completed an LT test to determine submaximal running speed with lactate collected and analyzed (Lactate Pro) via blood samples taken by finger prick. During subsequent submaximal running trials, metabolic and ventilatory measures were collected with a portable breath-by-breath analyzer (COSMED K5). Speed was controlled by a rider on a bicycle that was equipped with a speedometer. Spearmen’s Correlation was run between relative VO2 values and running power for males, females, and all subjects. RESULTS: There is a statistically significant, strong positive correlation between relative VO2 and running power for male (R=0.778; P<0.001), female (R=0.846; P<0.001), and combined male and female collegiate cross country runners (R=0.602; P<0.001). CONCLUSIONS: The results support that running power is positively related to VO2, which may indicate a strong relationship with running intensity.

Are Joint Kinetics Proximally Redistributed Following A Long Run In Well-trained Runners?

Proximal redistribution of joint work to the hip occurs following intensive running in novice runners [1] and might explain the reduced running economy following prolonged running [2]. These findings in novice might be different in well-trained runners due to their training status. PURPOSE: The purpose of this study was to assess if proximal redistribution of joint kinetics following a running bout is observed in well-trained runners. METHODS: 14 well-trained male runners with habitual rearfoot strike patterns (76±22km/week) completed 5 running trials at a speed equivalent to ±5% of their long run pace while 3D kinematic and ground reaction force data were collected before and after a treadmill run equal to 25% of weekly mileage (19±6km). Joint powers and work were calculated from these data using Visual3D. Percent contribution of each joint work relative to total lower limb joint work was computed. Paired samples t-tests were used to compare joint kinetics before and after the run (p < 0.05). Cohen’s d effect sizes were computed to assess mean difference magnitudes. RESULTS: Peak ankle negative power (Table 1) and hip negative relative work contribution (pre: 14.3±3.6%, post: 15.6±4.5%, p=0.041; d=0.33) showed significant pre- to post-run effects. Positive ankle (pre: 50.6±6.8%, post: 49.5±7.3%, p=0.35; d=0.16) and hip relative work (pre: 26.2±10.1%, post: 27.1±8.8%, p=0.53; d=0.10) were unaffected by the long run in these well-trained male runners. CONCLUSIONS: These findings suggest that previously reported distal-to-proximal shift in positive joint work in novice runners following a running bout [1] is not observed in well-trained male runners. This might be the result of chronic training exposure in these trained runners and suggest a preservation of mechanical joint output despite prolonged running exposure. Differences in run type (intense vs steady prolonged run), foot strike, and gender might also be responsible for these differences between studies.Table 1: Peak negative and positive joint powers (W·kg-1) before and after the prolonged run (mean±SD).

The Analysis of The Pacing Profiles Based on The Performance Level of The Finishers in The Istanbul Marathon

The aim of this study is to determine, on the basis of performance levels, running pace profiles of the male runners (n=2095) who completed the 40th International Istanbul Marathon in less than 6 hours. While 0-35 km of the marathon was divided into 5 km long sections, 35-42.2 km of it was determined as the last segment which was 7.2 km. The average speeds of the running pace of the athletes in the determined segments were calculated. Performance groups were evaluated in 8 different groups with the athletes completing the race in the finishing time slower than the winner’s race time. The difference between performance groups and successive segments was evaluated with Mixed Anova. The results of the Mixed Anova analysis showed that there were statistically significant differences between inter-segments race profiles depending on the performance level ( p <0.000). Overall, the athletes showed an increasing pace in all the performance groups in the first ten kilometers of the race ( p <0.001). The highest level of the performance group showed an even pace in the segments between 10 and 25 km, while it fell between 25 and 30 km and continue at this level between 30 and 35 km. In other groups, it was observed that the speeds fell inversely proportional to the performance in the segments between 10 and 35 km ( p <0.05). In the last 7.2 km segment, it was observed that the athletes with the highest level of performance had a decrease in pace and the rate of decrease in the pace was lower in the groups with lower performance level. Only in the slowest group of athletes, the pace was observed to increase in the last segment. Considering the whole race, it was seen that the athletes showed a pace profile close to the positive pace profile in general.

Intra-athlete and inter-group comparisons: Running pace and step characteristics of elite athletes in the 400-m hurdles.

The aim of this study was to investigate the running pace and step characteristics among various competitive-level 400-m hurdlers through inter-group and intra-athlete comparisons. We analysed spatiotemporal data involving the split time, mean step length (SL) and mean step frequency (SF) for 13 male world-class and 14 male national-level 400-m hurdlers. We analysed 16.5 ± 3.9 races for each world-class hurdler and 19.8 ± 6.0 races for each national-level hurdler (the total number of analysed runs was 491) using publicly available television and internet broadcasts. Inter-group comparisons showed that both first- and latter-halves split times of the world-class hurdlers were significantly shorter than those of the national-level hurdlers. In the latter-half phase, no significant differences of SL and SF were observed between the world-class and national level hurdlers. Intra-athlete comparisons showed that no athletes favoured only first-half phase in terms of running speed in short finish times. In contrast, finish times of all hurdlers were sensitive to running speed in the latter-half phase. In the latter half of the race, 18 of the 27 hurdlers were identified as being SF reliant during speed enhancements; running speed of the other 9 hurdlers were also sensitive to high SF. In conclusions, important findings regarding high performance in inter-group comparisons do not always corresponded with those in intra-athlete comparisons. All athletes and coaches should first prioritize maintaining high running speeds in the latter half of 400-m hurdles rather than in the first half of the race.

The Combined Effect of Continuous Run, Alternate Pace Run and Fartlek Training on Selected Physiological Variable among Male Athletes

The study aims to determine the effect of continuous run, alternate pace run and fartlek training on the selected physiological variable (Resting Pulse Rate) among the male athletes of Alagappa University affiliated colleges. The research involved a random subject selection of fifty athletes with age ranging from 17–25 years and had five equally divided groups namely experimental groups A, B, C, Dand control group E with 10 athletes each. The groups endured the training activities for twelve weeks with a schedule of thrice a week whereas the control group remained with no activities. The data procured in prior and after the training programme was examined with the application of Analysis of Covariance and the fixation of level of significance at 0.05. Scheffe's test was applied at the significance of ‘F’ ratio in order to evaluate the differences that occur significantly between the paired means. The study revealed that the selected physiological variable of the combined group with the three endurance trainings outperformed the other groups.

Isolated and Combined Effect of Continuous Run Alternate Pace Run on Selected Motor Fitness Physiological Haematological Variables among Male Athletes

Isolated and Combined Effect of Continuous Run Alternate Pace Run on Selected Motor Fitness Physiological Haematological Variables among Male Athletes

Enacting Phenomenological Gestalts in Ultra-Trail Running: An Inductive Analysis of Trail Runners' Courses of Experience.

Using an enactive approach to trail runners’ activity, this study sought to identify and characterize runners’ phenomenological gestalts, which are forms of experience that synthesize the heterogeneous sensorimotor, cognitive and emotional information that emerges in race situations. By an in-depth examination of their meaningful experiences, we were able to highlight the different typologies of interactions between bodily processes (e.g., sensations and pains), behaviors (e.g., actions and strategies), and environment (e.g., meteorological conditions and route profile). Ten non-professional runners who ran an ultra-trail running race (330 km, 24,000 m of elevation gain) volunteered to participate in the study. Data were collected in two steps: (1) collection of past activity traces (i.e., race maps, field notes, and self-assessment scales) and (2) enactive interviews using the past activity traces in which the runners were invited to relive their experience and describe their activity. The enactive interviews were coded using the course-of-experience methodology to identify the phenomenological gestalts that emerged from activity and scaffolded the runners’ courses of experience. The results revealed that runners typically enact three phenomenological gestalts: controlling global ease, enduring general fatigue and experiencing difficult situations, and feeling freedom in the running pace. These phenomenological gestalts were made up of specific behaviors, involvements, and meaningful situated elements that portrayed various ways of achieving an ultra-endurance performance in the race situation. They also highlighted how runners enact a meaningful world by acting in relation to the fluctuations in physical sensations and environmental conditions during an ultra-trail race. Practical applications for preparation, race management and sports psychology interventions are proposed to enrich the existing recommendations. In conclusion, this approach provides new research perspectives by offering a more holistic grasp of activity in trail running through an in-depth analysis of athletes’ experience. In doing so, we may expect that runners can connect these typical gestalts to their own personal experiences and stories as trail runners in order to sustain a viable approach to their sport.

ProjectRun21: Do running experience and running pace influence the risk of running injury—A 14-week prospective cohort study

ObjectivesThe health benefits from participation in half-marathon is challenged by a yearly running-related injury (RRI) incidence proportion exceeding 30%. Research in injury etiology is needed to successfully prevent injuries. The body’s load capacity is believed to play an essential role for injury development. Therefore, the purpose of ProjectRun21 was to investigate the association between load capacity defined as running experience and running pace, and RRI when following a specific half-marathon running schedule. DesignA 14-week prospective cohort study. MethodsA cohort of 784 healthy runners followed a specific half-marathon running schedule. Data on running activity was collected objectively using a Global-Positioning-System watch or smartphone. RRI were collected using e-mail-based weekly questionnaires. Primary exposures were running experience and running pace, dichotomized into a high and a low group for runners running less or more than 15km/week and faster or slower than 6min/km, respectively. Data was analyses through time-to-event models with cumulative risk difference (RD) as measure of association. ResultsA total of 136 participants sustained a RRI during follow-up. Although not statistically significant, all estimates indicate a tendency toward fewer injuries amongst runners categorized as having high experience (RD=−11.3% (−27.2% to 4.6%)) or high pace (RD=−17.4% (−39.0% to 4.5%)), and a combination of both high experience and high pace (RD=−8.1% (−22.3% to 6.1%)) compared with their counterpart peers. ConclusionsRunners covering less than 15km per week, and/or runs slower than 6min/km, may sustain more RRI than their counterpart runners.

Differences In Wearable Running Power On Three Different Surfaces During Submaximal Running

Running pace is one of the primary measures of running intensity, however, variations in grade and surface limit quantifying intensity solely based on pace. With the advent of wearable running power meters, runners can assess the external work stimulus inclusive of pace, grade, and surface. PURPOSE: To assess differences in running power (RP) on different surfaces, a Stryd running power meter was evaluated based on submaximal running on three different surfaces. METHODS: Eight collegiate cross country runners (male n=4, age=21.25±0.50 yrs, weight=63.45±9.73 kg, height=178.5±10.82 cm; female n=4, age=20±1.41 yrs, weight=56.45±4.95 kg, height=169.5±7.97 cm) participated in two trials of submaximal running at 85% of lactate threshold (LT) on each of three different surfaces: treadmill, grass, and track. All subjects completed a a VO2max and LT running test. For this investigation, sub-maximal running speed/pace was determined from the maximal effort / LT test. During subsequent submaximal running trials, ventilatory and metabolic measures and heart rate (HR) were collected with a portable breath by breath analyzer (COSMED K4B2) and HR monitor (Polar). For the track and grass submaximal running, the runners were paced by a cyclist maintaining a constant speed using a speedometer. ANOVAs were run between trials on all surfaces including treadmill, track and grass. RESULTS: The running power for the treadmill surface was significantly lower than both the grass and track (Mean±SE: RPtreadmill = 237±12.7 W*, RPgrass = 244±13.4 W, RPtrack = 242±13.0 W). There were no significant differences between grass and track surfaces (*p<0.05). CONCLUSIONS: This investigation found that running power (Stryd) is less when running on a treadmill compared to running on grass and a track which may indicate a different training stimulus when training on a treadmill versus other surfaces.

Running at submaximal speeds, the role of the intact and prosthetic limbs for trans-tibial amputees

BackgroundDynamic Elastic Response prostheses are designed to absorb and return strain energy in running. Past research has focused on running prostheses with a single toe spring designed for high speeds. Research questionTo determine how runners with amputation modulate the ground reaction force of each limb to run at different speeds using a general-purpose dynamic prosthesis which has a heel spring. MethodsOverground running data were collected in 16 recreational runners (8 transtibial amputee using their own BladeXT prosthesis and 8 controls) using Vicon Nexus V.2.5 with Kistler force plates. Participants ran at self-selected running pace, 70% and 130% of that pace. Vertical, braking and propulsion peak ground reaction forces and impulses and vertical loading and decay rates were analysed between limbs at each speed (ANOVA) and their association with speed assessed (simple linear regression). ResultsThe vertical, braking forces and impulses and propulsive force were significantly less (p < 0.05) on the prosthetic limb than controls at the faster speed, but there was no difference in the propulsive impulse. The intact limb did not evidence increased vertical force at any speed, but experienced increased braking (p < 0.05) compared to both prosthetic limb and controls at the slow speed. For all limbs, braking and propulsive peak forces, decay rate, step length and step frequency were strongly (r > 0.6) and significantly (p < 0.05) associated with speed. On the prosthetic limb vertical impulse was strongly and significantly negatively associated with speed and control’s braking impulse was associated with speed. SignificanceA leg-specific response was found at different speeds. On the prosthetic limb the technique was to brake less not propel more at higher speeds with reduced vertical drive. Running at self-selected speed could be used for fitness without inducing detrimental ground reaction forces on the intact limb or evoking asymmetry in step length and frequency.

Can the endurance training change the pacing strategy during 10 km running performance?

The aim of this study was to verify the effect of endurance training on the pacing strategy and analyse the risk of premature fatigue during the 10-km performance in moderately trained runners. Study participants were 14 runners (18–35 years) who had training prescribed with peak velocity (Vpeak) and its time limit (tlim). Three tests were performed on a treadmill: two maximum incrementals for VO2max and Vpeak and one for tlim. The 10-km running performance was evaluated on a 400-m track. The mean velocity, heart rate (HR) and rate of perceived exertion (RPE) were monitored at each trial of 10-km running performance. Evaluations were collected pre and after 4 weeks of endurance training. The RPE and HR increased linearly throughout the test, and the risk of fatigue decreased after 3 km. The pacing strategy used by the participants was the “U” running pace in pre- and post-training. There was improvement in the 10-km run after training (40.8 ± 2.8 vs. 39.6 ± 2.7 min). The study showed that 4 weeks of endurance training does not change the pacing strategy and the risk of premature fatigue. However, the training was responsible for improving the 10-km running performance.

External Feedback Does Not Affect Running Pace in Recreational Runners

External Feedback Does Not Affect Running Pace in Recreational Runners

Design of ProjectRun21: a 14-week prospective cohort study of the influence of running experience and running pace on running-related injury in half-marathoners

BackgroundParticipation in half-marathon has been steeply increasing during the past decade. In line, a vast number of half-marathon running schedules has surfaced. Unfortunately, the injury incidence proportion for half-marathoners has been found to exceed 30% during 1-year follow-up. The majority of running-related injuries are suggested to develop as overuse injuries, which leads to injury if the cumulative training load over one or more training sessions exceeds the runners’ load capacity for adaptive tissue repair. Owing to an increase of load capacity along with adaptive running training, the runners’ running experience and pace abilities can be used as estimates for load capacity. Since no evidence-based knowledge exist of how to plan appropriate half-marathon running schedules considering the level of running experience and running pace, the aim of ProjectRun21 is to investigate the association between running experience or running pace and the risk of running-related injury.MethodsHealthy runners using Global Positioning System (GPS) watch between 18 and 65 years will be invited to participate in this 14-week prospective cohort study. Runners will be allowed to self-select one of three half-marathon running schedules developed for the study. Running data will be collected objectively by GPS. Injury will be based on the consensus-based time loss definition by Yamato et al.: “Running-related (training or competition) musculoskeletal pain in the lower limbs that causes a restriction on or stoppage of running (distance, speed, duration, or training) for at least 7 days or 3 consecutive scheduled training sessions, or that requires the runner to consult a physician or other health professional”.Running experience and running pace will be included as primary exposures, while the exposure to running is pre-fixed in the running schedules and thereby conditioned by design. Time-to-event models will be used for analytical purposes.DiscussionProjectRun21 will examine if particular subgroups of runners with certain running experiences and running paces seem to sustain more running-related injuries compared with other subgroups of runners. This will enable sport coaches, physiotherapists as well as the runners to evaluate their injury risk of taking up a 14-week running schedule for half-marathon.

Physiological response to an experimental 100 m flying pace race in Icelandic horses and effect of rider

This study evaluated the physiological response to an experimental 100 m flying pace race (EPR) in Icelandic horses with pace-competition experience, and whether there was an effect of rider. A cross-over design with nine horses and two riders was used. The EPR was performed twice (once with each rider) with four days of rest in-between. The EPR consisted of two runs (I and II), of which at least 100 m was in pace at full speed according to international competition rules. Plasma lactate concentration increased and was greater after pace run II than I (18.5±1.3 vs 11.9±0.7 mmol/l; P&lt;0.001). Heart rate was higher during pace run I than II (207±3 vs 205±3; P=0.02). Heart rate and Lact had not recovered 30 min post exercise but Hct was back to resting level after 30 min recovery. Speed did not differ between riders and pace runs (pooled mean ± standard deviation of pace runs: 10.4±0.7 m/s, range 9.2-12.1 m/s) but HR and Lact were higher from warm-up and until 30 min recovery with rider 1 than 2 (P&lt;0.001). There was a negative correlation between post EPR Lact with rider 1 and previous best record (r2=0.72, P=0.032). To conclude, a 100 m flying pace race in the Icelandic horse is a high-intensity exercise and anaerobic metabolism is crucial for performance. The rider had an effect on the physiological response but it is unclear if it was due to body weight, riding style or both. The practical relevance of the differences observed between riders remains to be proven but our results indicate that they may have limited impact on single day competitions since the speed was the same with the two riders.

The Ability of Sagittal Plane Kinematic Variables to Predict Loading in Different Populations of Runners

It is known that sagittal plane kinematics are able to predict loading in runners. This may be of use to clinicians who don’t have access to force measurement devices. However, running biomechanics differ between genders and age groups. Thus it may be that models used to predict loading in demographically distinct groups of runners need to be specific to age and gender. PURPOSE: To determine if kinematic predictors of kinetic variables during running apply across genders and age groups. METHODS: Sagittal plane kinematics and kinetics were assessed in young male (YM: n=13, age=23.1 ± 2.3 yrs, mass=77.0 ± 12.1 kg, height=1.79 ± 0.08 m, velocity=3.32 ± 0.48 m/s) and middle-aged female runners (MF: n=28, age=47.3 ± 7.0 yrs, mass=63.7 ± 7.8 kg, height=1.66 ± .07 m, velocity=2.55 ± 0.37 m/s) using a 5 camera motion analysis system (Qualysis, Goteborg, Sweden) running on an instrumented treadmill (Treadmetrix, Park City, Utah) at their preferred running pace. Kinematics (knee flexion at initial contact, foot angle at initial contact, step position, peak knee flexion and COM excursion) were the independent variables; kinetics (average vertical loading rate, braking impulse, knee power absorption and peak knee extension moment and peak vertical ground reaction force) were the dependent variables. Linear regression models were developed to predict loading in both groups (α=0.05). RESULTS: In both YM and MF, sagittal plane kinematics were useful in predicting peak knee moment (YM: R2=0.56, p=.002; MF: R2=0.47,p=.0002), knee power absorption (YM: R2=0.78, p=.0002; MF: R2=0.55, p<.0001), braking impulse (YM: R2=0.66, p=0.01; MF: R2=0.67, p<.0001), and peak vertical ground reaction force (YM: R2=0.31, p=0.03; MF: R2=0.23, p=0.02). Peak knee flexion appeared in the most models (peak knee moment, knee power absorption and braking impulse for both men and women), and thus may be the most useful single kinematic variable to assess loading across age groups and genders. In all models, greater knee flexion was associated with increased magnitude of loading. Average vertical loading rate could not be predicted using the chosen kinematics in either group. CONCLUSIONS: When equipment for kinetic assessment is not available, sagittal plane gait analysis may be a useful tool for clinicians to estimate loading in runners.

Medial shoe-ground pressure and specific running injuries: A 1-year prospective cohort study.

Achilles tendinitis, plantar fasciopathy and medial tibial stress syndrome injuries (APM-injuries) account for approximately 25% of the total number of running injuries amongst recreational runners. Reports on the association between static foot pronation and APM-injuries are contradictory. Possibly, dynamic measures of pronation may display a stronger relationship with the risk of APM-injuries. Therefore, the purpose of the present study was to investigate if running distance until the first APM-injury was dependent on the foot balance during stance phase in recreational male runners. Prospective cohort study. Foot balance for both feet was measured during treadmill running at the fastest possible 5000-m running pace in 79 healthy recreational male runners. Foot balance was calculated by dividing the average of medial pressure with the average of lateral pressure. Foot balance was categorized into those which presented a higher lateral shod pressure (LP) than medial pressure, and those which presented a higher medial shod pressure (MP) than lateral pressure during the stance phase. A time-to-event model was used to compare differences in incidence between foot balance groups. Compared with the LP-group (n=59), the proportion of APM-injuries was greater in the MP-group (n=99) after 1500km of running, resulting in a cumulative risk difference of 16%-points (95% CI=3%-point; 28%-point, p=0.011). Runners displaying a more medial pressure during stance phase at baseline sustained a greater amount of APM-injuries compared to those displaying a lateral shod pressure during stance phase. Prospective studies including a greater amount of runners are needed to confirm this relationship.

Activity Profiles and Positional Differences of Handball Players During the World Championships in Qatar 2015.

Handball is an Olympic sport played indoors by 6 court players and 1 goalkeeper with rolling substitutions. Limited data exist on elite players competing in a world championship, and virtually no information exists on the evolution of time-motion performance over the course of a long tournament. To analyze time-motion characteristics of elite male handball players of the last world championships, played in Qatar in 2015. 384 handball players from 24 national teams. The athletes were analyzed during 88 matches using a tracking camera system and bespoke software (Prozone Handball v. 1.2, Prozone, Leeds, UK). The average time on court (N = 2505) during the world championships for all players was 36:48 ± 20:27 min. Goalkeepers and left and right wings were on court most of the playing time (GK 43.00 ± 25:59 min; LW 42:02 ± 21:07 min; RW 43:44 ± 21:37 min). The total distance covered during each game (2607.5 ± 1438.4 m) consisted mostly of walking and jogging. The cumulative distance covered during the tournament was 16,313 ± 9423.3 m. Players performed 857.2 ± 445.7 activity changes with a recovery time of 124.3 ± 143 s. The average running pace was 78.2 ± 10.8 m/min. There was no significant difference between high-ranked and lower-ranked teams in terms of distance covered in different locomotion categories. Specific physical conditioning is necessary to maximize performance of handball players and minimize the occurrence of fatigue when performing in long tournaments.

Kinematic alterations after two high-intensity intermittent training protocols in endurance runners

PurposeThis study aimed to evaluate running kinematic characteristics during the early and late stages of 2 high-intensity intermittent training (HIIT) protocols with similar external load but different average running pace, as well as to compare the fatigue-induced changes during both HIIT protocols at a kinematic level. MethodsEighteen endurance runners were tested on a track on 2 occasions: 10 runs of 400 m with 90–120 s recovery between running bouts (10 × 400 m), and 40 runs of 100 m with 25–30 s recovery between running bouts (40 × 100 m). Heart rate was monitored during both protocols; blood lactate accumulation and rate of perceived exertion were recorded after both exercises. A high-speed camera was used to measure sagittal-plane kinematics at the first and last runs during both HIIT protocols. The dependent variables were spatial-temporal parameters (step length and contact and flight time), joint angles during support (relative angles of the hip, knee, and ankle), and foot strike pattern. ResultsHigh levels of exhaustion were reached by the athletes during both workouts (blood lactate accumulation >12 mmol/L, rate of perceived exertion >15; peak heart rate (HRpeak) > 176 bpm). A within-protocol paired t test (first vs. last run) revealed no significant changes (p ≥ 0.05) in kinematic variables during any of the HIIT sessions. A between-protocol comparison with the first run of each protocol revealed the effect of running speed on kinematics: +2.44 km/h during the 40 × 100 m: shorter contact and flight time (p ≤ 0.01) and longer step length (p = 0.001); greater hip flexion (p = 0.031) and ankle extension (p = 0.001) at initial contact; smaller knee and ankle flexion (p < 0.001) at midstance; and greater hip extension at toe-off (p < 0.001). ConclusionHIIT sessions including runs for 15–90 s and performed at intensity above the velocity associated with maximal oxygen uptake did not consistently perturb the running kinematics of trained endurance runners.