GPS-Based Evaluation of Activity Profiles in Elite Downhill Mountain Biking and the Influence of Course Type

This study aimed to profile the activity patterns of elite downhill (DH) mountain bikers during off-road descending, and to determine the influence of course types on activity patterns. Six male elite DH mountain bikers (age 20 ± 2 yrs; stature 178.8 ± 3.1 cm; body mass 75.0 ± 3.0 kg) performed single runs on one man-made (MM) and one natural terrain (NT) DH courses under race conditions. A 5 Hz global positioning systems (GPS) unit, including a 100 Hz triaxial accelerometer, was positioned in a neoprene harness between the C7 and T2 vertebrae on each rider. GPS was used to determine the temporal characteristics of each run for velocity, run time, distance, effort, heart rate (HR), rider load (RLd) which reflects instantaneous rate of change in acceleration, and accumulated rider load (RLdAcc), which reflects change in acceleration over the event duration. Significant differences were found between NT and MM courses for mean velocity (p<.001), peak velocity (p=.014), mean RLd (p=.001) and peak RLd (p=.002). Significant differences were also found both within and between courses for all velocity parameters, when analysed by intensity zone (p<.05). No significant differences were found between courses for HR parameters by zone, though significant differences were revealed between HR zones within courses (p<.05). This study indicates that course terrain has a significant impact on the activity profiles of DH and that GPS can provide a practical means of monitoring these differences in activity

The influence of swim, cycle and run performance on overall race outcome at the off-road triathlon world championships

The purpose of this study was to determine whether swim, cycle or run performance best predicts overall position during the off-road triathlon world championships. Data were collected for the top 10 finishers at each male and female world championships between 2007 and 2016. Linear regression was used to predict the influence of each discipline on finishing in the top 10 overall over the 10 years, whilst one-way between subjects analysis of variance (ANOVA’s) were conducted to determine any differences in mean overall finishing time, swim, cycle and run times of the top 10 finishers between years. Cycling best predicted overall position (R2 = 0.31), followed by the run and swim (R2 = 0.17 and 0.16, respectively) for males. For females the run best predicted overall performance (R2 = 0.46), then the cycle and swim (R2 = 0.26 and 0.15, respectively). ANOVA analyses found significant differences for males in swim time (F9,99 = 4.32; p < 0.001; ηp2 = 0.30), cycle time (F9,99 = 48.33; p < 0.001; ηp2 = 0.83), run time (F9,99 = 22.89; p < 0.001; ηp2 = 0.70) and overall time (F9,99 = 59.12; p < 0.001; ηp2 = 0.86). Similarly, significant differences were also found for females in swim time (F9,99 = 3.60; p = 0.001; ηp2 = 0.26), cycle time (F9,99 = 37.14; p < 0.001; ηp2 = 0.79), run time (F9,99 = 13.77; p < 0.001; ηp2 = 0.58) and overall time (F9,99 = 28.17; p < 0.001; ηp2 = 0.74) by year. Results indicate there are differences in the influence of each discipline for males and females over the 10 years and by each year. Environmental conditions and competitive background may be influential in these findings

The influence of swim, cycle and run performance on overall race outcome at the off-road triathlon world championships

The purpose of this study was to determine whether swim, cycle or run performance best predicts overall position during the off-road triathlon world championships. Data were collected for the top 10 finishers at each male and female world championships between 2007 and 2016. Linear regression was used to predict the influence of each discipline on finishing in the top 10 overall over the 10 years, whilst one-way between subjects analysis of variance (ANOVA’s) were conducted to determine any differences in mean overall finishing time, swim, cycle and run times of the top 10 finishers between years. Cycling best predicted overall position (R2 = 0.31), followed by the run and swim (R2 = 0.17 and 0.16, respectively) for males. For females the run best predicted overall performance (R2 = 0.46), then the cycle and swim (R2 = 0.26 and 0.15, respectively). ANOVA analyses found significant differences for males in swim time (F9,99 = 4.32; p < 0.001; ηp2 = 0.30), cycle time (F9,99 = 48.33; p < 0.001; ηp2 = 0.83), run time (F9,99 = 22.89; p < 0.001; ηp2 = 0.70) and overall time (F9,99 = 59.12; p < 0.001; ηp2 = 0.86). Similarly, significant differences were also found for females in swim time (F9,99 = 3.60; p = 0.001; ηp2 = 0.26), cycle time (F9,99 = 37.14; p < 0.001; ηp2 = 0.79), run time (F9,99 = 13.77; p < 0.001; ηp2 = 0.58) and overall time (F9,99 = 28.17; p < 0.001; ηp2 = 0.74) by year. Results indicate there are differences in the influence of each discipline for males and females over the 10 years and by each year. Environmental conditions and competitive background may be influential in these findings

The Power Output Characteristics of Downhill Mountain Biking

Purpose: To determine the performance characteristics of field-based Downhill Mountain biking (DH) and to identify the best methods of assessment for DH type activity. Methods: Twelve trained male cyclists of differing experience levels (age 31.4 ± 9.8 yrs, mean ± s.d.), performed a single laboratory-based intermittent cycle test consisting of 12 all out efforts, separated by periods of passive recovery ranging from 5 to 15 seconds and a continual incremental ramp test to exhaustion. Power output was recorded using a Polar S710 heart rate monitor and power sensor kit and a Schoberer Rad Messetechnik (SRM) Powermeter systemduring each test. Additionally, seventeen national level trained, male downhill cyclists (age 27.1 ± 5.1 yrs) performed two timed field-based runs of a measured DH course. An SRM Powermeter was used to record power, cadence and speed. Heart rate was again recorded via a Polar S710 monitor. Results: During intermittent tests significant differences (p<0.05) in power were found at 8 of the 12 efforts. A significant difference (p<0.001) was also found when power was averaged over all 12 intervals. Mean power was 556 ± 102 W and 446 ± 61 W for the SRM and S710 respectively. The 5710 underestimated power by an average of 23% with random errors of */ 24% when compared to the SRM. Random errors ranged from 36% to 141% with the median being 51%. Significant differences (p<0.001) were also found between the two systems during the incremental ramp tests. Mean power output was 189 ± 51 W and 212 ± 49 W for the SRM and S710 respectively. The 5710 overestimated power by an average of 11% over the SRM. Random errors ranged from 21% to 67% with the median being 13%. During field-testing peak power was 834 ± 129 W. Mean power (75 W) accounted for only 9% of peak values. Paradoxically, mean heart rate was 168 ± 9 beats.min-1, accounting for 89% of agepredicted maximum heart rate. Mean cadence (28 ± 20 revs.min -1) was significantly related to speed (r = 0.51; p<0.01). Power and cadence were not significantly related to run time or any other variable. Conclusions: Results indicated there was little agreement between the two ergometer systems. The Polar S710 did not provide a valid measure of power during intermittent DH type cycling activity, nor did it provide a valid measure for scientific/elite use during continuous type cycling activity. Errors in the 5710 system were potentially influenced by chain vibration and sampling rates. Field results support the intermittent nature of DH Mountain biking. The poor relationships between power and cadence to run time suggest they are not essential pre-requisites to performance in DH and indicate the importance of riding dynamics to overall performance. Keywords: Downhill, Mountain biking, power outpu

The Effects of Bicycle Geometry on Sprint Triathlon Running Performance

Previous research has shown that riding with a steeper (81°) than normal (73°) bicycle seat tube angle (STA) can improve subsequent run performance during Olympic distance triathlon that involve a 1500 m swim, 40 km cycle and 10 km run. However, such races often utilise pacing strategies during the run phase that may have influenced previous findings. Conversely, Sprint distance triathlons (750 m swim, 20 km cycle and 5 km run) are generally performed at a higher intensity, both during the cycle and run legs. Few studies have focused on Sprint triathlons, therefore, the purpose of this study was to investigate the effect cycling with different STA’s had on subsequent sprint triathlon running performance. Ten trained amateur male triathletes (34.8 ± 10.9 years), completed two 20 km time trials on a cycle ergometer, one with a STA of 73° and one with a STA of 81°. Both conditions were followed immediately by a 5 km treadmill based running time trial and were completed as fast as possible. Time (min:s), heart rate (Beats.min-1), oxygen consumption (ml.kg.min-1) and rate of perceived exertion (RPE) were recorded for both run and cycle legs. Additionally, during the cycle leg, mean power output (W), mean cadence (rpm) and mean velocity (km.h-1) were recorded. For the run leg, velocity (m.s-1), stride length (SL, in m) and stride frequency (SF, in Hz) were additionally recorded. Running time improved significantly following cycling with the 81° STA compared to 73° STA (27:10 ± 3:09 vs. 27:59 ± 3:18 min:s respectively; p=.006; ES=0.25), along with running velocity (3.13 ± 0.37 vs. 3.04 ± 0.37 m.s-1 for 81° and 73° respectively; p=.007; ES=0.24). Stride length also increased significantly following the cycle with the 81° STA (2.20 ± 0.26 vs. 2.12 ± 0.27 m for 81° and 73° respectively; p=.007; ES=0.30). Overall cycle+run time was also significantly reduced in the 81° condition (63:31 ± 6:08 vs. 64:23 ± 5:10 min:s for 81° and 73° respectively; p=.042; ES=0.15). These results suggest that cycling on a bicycle with a steeper STA improves subsequent running and overall performance during a simulated sprint triathlon, possibly due to changes in lower limb biomechanics

Agreement Between the Stages Cycling and SRM Powermeter Systems during Field-Based Off-Road Climbing.

The aim of this study was to determine the agreement between two portable cycling powermeters for use doing field based mountain biking. A single participant performed 15 timed ascents of an off-road climbs. The participants bicycle was instrumented with Stages Cycling and SRM powermeters. Mean and peak power output and cadence were recorded at 1 s intervals by both systems. Significant differences were determined using paired t-tests, whilst agreement was determined using 95% ratio limits of agreement (LoA). Significant differences were found between the two systems for mean power output (p<.001), with the Stages powermeter under reporting power by 8 % compared to the SRM. LoA for mean power output were 0.92 ×÷ 1.02 (95% LoA = 0.90 – 0.93). Peak power output was also significantly lower with the Stages powermeter (p=.02) by 5 % when compared to the SRM powermeter. LoA for peak power output were 0.94 ×÷ 1.09 (95% limits of agreement = 0.87 – 1.03). Significant differences were found for mean cadence between the two powermeters (p=.009), with LoA being 0.99 ×÷ 1.01 (95% limits of agreement = 0.99 – 1.00). This study found that though the Stages Cycling powermeter provided a reliable means of recording power output and cadence, the system significantly underestimated mean and peak power output when compared with the SRM system. This may in part be due to differences in strain gauge configuration and the subsequent algorithms used in the calculation of power output and the potential influence of bilateral imbalances within the muscles may have on these calculations

Influence of Absolute versus relative L-arginine Dosage on 1 km and 16.1 km time trial performance in trained cyclists.

This investigation aimed to determine the effects of L-arginine supplementation on cycling time trial (TT) performance. Eight trained male cyclists performed 1 and 16.1km time trials on three occasions, control (CON), absolute (ABS) and relative (REL) loading. Participants consumed 500ml of water with either 6g (ABS), 0.15 g·kg-1 body mass (REL) of L-arginine or water (CON) 90min prior to testing. Time to completion, mean power output (Wmean) and post-exercise lactate (La) were recorded for each TT. Time to completion decreased non-significantly for 1 and 16.1km TT’s during ABS and REL trials compared to CON. Wmean was significantly different between CON and REL during 16.1 km TT (196.19 ± 32.40W and 215.81 ± 31.56W). Blood lactates was significantly different between CON and ABS for the 1 km TT (p = 0.04) (13.59 ± 1.21 mmol·L-1 and 12.38 ± 0.70 mmol·L-1, respectively) and between CON and ABS (p = 0.04) (9.11 ± 2.91mmol·L-1 and 7.64 ± 3.01mmol·L-1, respectively) and CON and REL (9.11 ± 2.91mmol·L-1 and 7.15 ± 2.96mmol·L-1, respectively) for 16.1km TT. These results indicate L-arginine supplementation does not significantly improve cycling TT performance, though there was a trend towards reduced time to completion and increased mean power output, and that relative doses appear more effective than absolute doses

Concussion knowledge and attitudes amongst competitive cyclists

The purpose of this study was to examine the concussion knowledge and attitudes of UK competitive road cyclists to identify gaps in knowledge and assess attitudes. This was a cross-sectional study using 118 UK competitive cyclists, spanning a range of ages and abilities. An adapted Rosenbaum Concussion Knowledge and Attitudes Survey (RoCKAS) was administered to the participants. The RoCKAS contained separate knowledge and attitude sections (possible scores ranged from 0-33 and 15-75, respectively). A cohort analysis was conducted to examine for differences in attitudes amongst the participants. The mean score for concussion knowledge was 26.4 ± 4.12 and 63.1 ± 6.4 for concussion attitude. Statistically significant differences were found in attitudes between the 49-58 age group and the 19-28 age group (p=0.013). Significant differences were also found between competitive cyclists and recreational cyclists who trained but did not race. The results of this study suggest that UK competitive cyclists have moderate concussion knowledge and good concussion symptom recognition. A cohort analysis shows that youth are less concerned about concussion than older participants and higher ability groups were associated with more dangerous attitudes. These findings can help inform targeted educational interventions in cycling to improve concussion awareness, reporting behaviors, and concussion management behaviors

Influence of Course Type on Upper Body Muscle Activity in Elite Cross-Country and Downhill Mountain Bikers During Off Road Downhill Cycling

This study aimed to investigate upper body muscle activity using surface electromyography (sEMG) in elite cross-country (XCO) and downhill (DH) cyclists during off road descending and the influence of man-made (MM) and natural terrain (NT) descents on muscle activity. Twelve male elite mountain bikers (n=6 XCO; age 23 ± 4 yrs; stature 180.5 ± 5.6 cm; body mass 70.0 ± 6.4 kg and n=6 DH; age 20 ± 2 yrs; stature 178.8 ± 3.1 cm; body mass 75.0 ± 3.0 kg) took part in this study. sEMG were recorded from the left biceps brachii, triceps brachii, latissimus dorsi and brachioradialis muscles and expressed as a percentage of maximal voluntary isometric contraction (% MVIC). Both groups performed single runs on different MM and NT courses specific to their cycling modality. Significant differences in mean % MVIC were found between biceps brachii and triceps brachii (p=.016) and triceps brachii and latissimus dorsi (p=.046) during MM descents and between biceps brachii and triceps brachii (p=.008) and triceps brachii and latissimus dorsi (p=.031) during NT descents within the DH group. Significant differences in mean % MVIC were found between biceps brachii and brachioradialis (p=.022) for MM runs and between biceps brachii and brachioradialis (p=.013) for NT runs within the XCO group. Upper body muscle activity differs according to the type of downhill terrain, and appears to be specific to DH and XCO riders. Therefore, the discipline specific impact on muscle activation and the type of course terrain ridden should be considered when mountain bikers engage in upper body conditioning programmes

The influence of different Cardan sequences on three-dimensional cycling kinematics

Purpose. Three-dimensional (3-D) kinematics are widely utilized to quantify movement in cycling analyses. Three-dimensional angular kinematics are obtained using the Euler/Cardan technique, however, Cardan angles are influenced by their ordered sequence and may affect the resultant angular parameters. An XYZ sequence of rotations is currently recommended, although this technique may not always be appropriate when coronal and transverse plane angles are quantified. This study aimed to determine the influence of the six available Cardan sequences on 3-D lower extremity kinematics during cycling. Methods. Kinematic information was obtained from twelve cyclists using an optoelectronic 3-D motion capture system operating at 250 Hz. Repeated measures ANOVAs were used to compare the kinematic parameters obtained using the six Cardan sequences, and intraclass correlations were employed to detect the presence of crosstalk across planes. Results. The results show that discrete kinematic parameters in the sagittal, coronal and transverse planes were significantly greater when using the YXZ and ZXY sequences. It was also observed that these sequences were associated with the strongest correlations from the sagittal plane and also exhibited evidence of gimbal lock. Conclusions. The results suggest that the accurate representation of 3-D kinematics during cycling should continue utilizing the XYZ sequence and avoid the use of the YXZ and ZXY sequences