Comparison of Physiological Responses and Performance Between Mountain Bicycles With Differing Suspension Systems

2011 ◽  
Vol 6 (4) ◽  
pp. 546-558 ◽  
Author(s):  
Jeffrey E. Herrick ◽  
Judith A. Flohr ◽  
Davis L. Wenos ◽  
Michael J. Saunders
Keyword(s):  
Physiological Responses ◽  
Time Trial ◽  
Rear Wheel ◽  
Final Time ◽  
Suspension Systems ◽  
Performance Effects ◽  
Race Conditions ◽  
Cross Country ◽  
And Performance ◽  
Maximal Time

Purpose:This study compared the metabolic and performance effects of riding front-only suspension (FS) and front-and-rear suspension (FRS) mountain bicycles on an off-road course that simulated competitive cross-country race conditions (>105 min in duration, with ∼70% of time spent riding uphill).Methods:Seven competitive mountain bikers (73.8 ± 7.6 kg; 61.0 ± 4.3 mL·kg–1·min–1) completed two randomized FS and FRS trials. Bikes were similar, excluding rear wheel suspension on the FRS, which increased bike weight by ∼2 kg. Each trial consisted of four laps of rugged 8 km trail with 154 m of elevation gain per lap. The first three laps were performed at ∼70% of VO2max; VO2, HR, and RPE were collected during the first and third laps. The final lap was performed as a maximal time-trial effort.Results:During the first and third laps, VO2, HR, and RPE were similar between FS and FRS. However, FS was significantly faster than FRS during the ascending segment of the course (17.6 ± 2.9 vs 18.9 ± 3.4 min, P = .035), despite similar VO2 (P = .651). Although not statistically significant, FRS tended to be faster than FS during the descending portion of the course (8.1 ± 2.0 vs 9.1 ± 2.1, P = .067) at similar VO2. Performance during the final time-trial lap was significantly faster for FS than FRS (24.9 ± 3.9 min, 27.5 ± 4.9 min, P = .008).Conclusion:FS was faster than FRS over a course that simulated competitive cross-country race conditions. The faster times were likely the result of improved cycling economy during ascending, which were at least partially influenced by the lighter weight of the FS.

scholarly journals Corporate Governance Structures and Performance of Firms in Asian Markets: a Comparative Analysis Between Singapore and Vietnam

2016 ◽  
Vol 7 (2) ◽  
pp. 112-140 ◽  
Author(s):  
Nguyen Van Tuan ◽  
Nguyen Anh Tuan
Keyword(s):  
Corporate Governance ◽  
Comparative Analysis ◽  
Financial Performance ◽  
Size Composition ◽  
Governance Structures ◽  
Country Level ◽  
Performance Effects ◽  
Leadership Structure ◽  
Cross Country ◽  
And Performance

A cross-country comparative analysis of corporate governance structures and financial performance of publicly listed companies in Singapore and Vietnam, covering a four-year period from 2008 to 2011, is undertaken in this study. More specifically, the similarities and differences in the corporate governance structures and financial performance of the companies are compared and interpreted in the institutional context of each market. On an average basis, we find that the size, composition and diversity of the boards in these two markets are statistically significantly different. In contrast, there is no statistical evidence to reject the similarities in ownership structure, board leadership structure, and financial performance between the firms of the two markets. In addition, our comparative analysis on the corporate governance structures–financial performance nexus also reveals that the performance effects of corporate governance structures vary significantly between the two markets, thus supporting the view that the performance effects of corporate governance structures are country-specific. Our findings suggest that country-level characteristics should be captured when modelling the corporate governance–firm performance relationship in cross-country comparative corporate governance research.

scholarly journals Laboratory- and field-based performance-predictions in cross-country skiing and roller-skiing

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256662
Author(s):  
Rune Kjøsen Talsnes ◽  
Guro Strøm Solli ◽  
Jan Kocbach ◽  
Per-Øyvind Torvik ◽  
Øyvind Sandbakk
Keyword(s):  
National Level ◽  
Time Trial ◽  
Strongly Correlated ◽  
Performance Indices ◽  
Performance Predictions ◽  
Double Poling ◽  
Individual Distance ◽  
Cross Country Skiing ◽  
Cross Country ◽  
And Performance

The purpose of the present study was to investigate how various laboratory- and field-based tests predict on-snow cross-country (XC) skiing and roller-skiing performance. Thirty-three national-level male XC skiers (19.0±2.5 years, maximal oxygen uptake [VO2max] 70.8±4.7 mL·min-1·kg-1) performed a 13.6-km roller-ski skating competition tracked by a global positioning system (GPS), which together with individual distance International Ski Federation (FIS) points was used to assess their performance level. On separate days, time in a 6.4-km uphill running time-trial (RUN-TT) and 1.3-km uphill roller-ski double-poling time-trial (DP-TT) was measured in the field and performance indices determined while running and roller-ski skating in the laboratory. The mean finishing times for the RUN-TT and the DP-TT showed moderate to large correlations with distance FIS points and performance in the roller-ski skating competition (r = 0.56–0.72; all p<0.05). RUN-TT was more strongly correlated with distance FIS points than DP-TT (r = 0.72 versus 0.56; p<0.05). Performance indices and VO2max in incremental running and roller-ski skating in the laboratory showed large to very large correlations with distance FIS points and roller-skiing performance (r = 0.50–0.90; all p<0.05). Performance indices and VO2max in running tended to be more strongly correlated with roller-skiing performance than corresponding values obtained while roller-ski skating (all p<0.10). The present findings suggest that both laboratory performance indices and field-based performance tests provide valid predictions of XC skiing and roller-skiing performance in a heterogeneous group of male XC skiers, with test values obtained in running tending to be more strongly correlated with XC skiing performance than those found for technique-specific modalities on roller skis. However, more sophisticated and mode-specific testing might be required for more homogenous groups of elite XC skiers.

Cross-Country Skiing and Postexercise Heart-Rate Recovery

2015 ◽  
Vol 10 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Laurent Mourot ◽  
Nicolas Fabre ◽  
Erik Andersson ◽  
Sarah Willis ◽  
Martin Buchheit ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Recovery ◽  
Time Trial ◽  
Upper Body ◽  
Clear Correlation ◽  
Trial Time ◽  
Cross Country Skiing ◽  
Cross Country ◽  
And Performance ◽  
Intensity Of Exercise

Postexercise heart-rate (HR) recovery (HRR) indices have been associated with running and cycling endurance-exercise performance. The current study was designed (1) to test whether such a relationship also exists in the case of cross-country skiing (XCS) and (2) to determine whether the magnitude of any such relationship is related to the intensity of exercise before obtaining HRR indices. Ten elite male cross-country skiers (mean ± SD; 28.2 ± 5.4 y, 181 ± 8 cm, 77.9 ± 9.4 kg, 69.5 ± 4.3 mL · min−1 · kg−1 maximal oxygen uptake [VO2max]) performed 2 sessions of roller-skiing on a treadmill: a 2 × 3-km time trial and the same 6-km at an imposed submaximal speed followed by a final 800-m time trial. VO2 and HR were monitored continuously, while HRR and blood lactate (BLa) were assessed during 2 min immediately after each 6-km and the 800-m time trial. The 6-km time-trial time was largely negatively correlated with VO2max and BLa. On the contrary, there was no clear correlation between the 800-m time-trial time and VO2, HR, or BLa. In addition, in no case was any clear correlation between any of the HRR indices and performance time or VO2max observed. These findings confirm that XCS performance is largely correlated with VO2max and the ability to tolerate high levels of BLa; however, postexercise HRR showed no clear association with performance. The homogeneity of the group of athletes involved and the contribution of the arms and upper body to the exercise preceding determination of HRR may explain this absence of a relationship.

Physiological and Performance Responses to a Preseason Altitude-Training Camp in Elite Team-Sport Athletes

2013 ◽  
Vol 8 (4) ◽  
pp. 391-399 ◽  
Author(s):  
Blake D. McLean ◽  
David Buttifant ◽  
Christopher J. Gore ◽  
Kevin White ◽  
Carsten Liess ◽  
...  
Keyword(s):  
Sea Level ◽  
Time Trial ◽  
Team Sport ◽  
Altitude Training ◽  
Moderate Altitude ◽  
Running Performance ◽  
Performance Effects ◽  
And Performance ◽  
The Individual ◽  
Individual Responsiveness

Purpose:Little research has been done on the physiological and performance effects of altitude training on team-sport athletes. Therefore, this study examined changes in 2000-m time-trial running performance (TT), hemoglobin mass (Hbmass), and intramuscular carnosine content of elite Australian Football (AF) players after a preseason altitude camp.Methods:Thirty elite AF players completed 19 days of living and training at either moderate altitude (~2130 m; ALT, n = 21) or sea level (CON, n = 9). TT performance and Hbmass were assessed preintervention (PRE) and postintervention (POST1) in both groups and at 4 wk after returning to sea level (POST2) in ALT only.Results:Improvement in TT performance after altitude was likely 1.5% (± 4.8–90%CL) greater in ALT than in CON, with an individual responsiveness of 0.8%. Improvements in TT were maintained at POST2 in ALT. Hbmass after altitude was very likely increased in ALT compared with CON (2.8% ± 3.5%), with an individual responsiveness of 1.3%. Hbmass returned to baseline at POST2. Intramuscular carnosine did not change in either gastrocnemius or soleus from PRE to POST1.Conclusions:A preseason altitude camp improved TT performance and Hbmass in elite AF players to a magnitude similar to that demonstrated by elite endurance athletes undertaking altitude training. The individual responsiveness of both TT and Hbmass was approximately half the group mean effect, indicating that most players gained benefit. The maintenance of running performance for 4 wk, despite Hbmass returning to baseline, suggests that altitude training is a valuable preparation for AF players leading into the competitive season.

scholarly journals Three km Track Time Trial Performance Changes after HIIT in Competitive Cross-Country Skiers

2021 ◽  
Vol 9 (1) ◽  
pp. 15
Author(s):  
Anneke Winegarden ◽  
Constance Lebrun ◽  
Louis Passfield ◽  
Patricia Doyle-Baker
Keyword(s):  
Time Trial ◽  
Interval Training ◽  
High Intensity Interval Training ◽  
Repeated Testing ◽  
Physiological Mechanisms ◽  
Quasi Experimental ◽  
Cross Country ◽  
And Performance ◽  
High Intensity Interval ◽  
Field Setting

Background: Limited research surrounding sex differences in fatigue and performance after high intensity interval training (HIIT) exists in the field setting. While lab-based protocols provide a controlled environment, physiological mechanisms of fatigue and performance response in competitive athletes are best measured by time-trial (TT). Few studies, however, have investigated fatigue in TT performance while controlling for the menstrual cycle (MC). Objective: The study investigated the influence of sex and MC phase on 3km track TT performance after a HIIT session in Competitive Cross Country (XC) skiers. Methods: A quasi-experimental design was employed and athletes over the age of 16 years (30F, 9M), were recruited from across Canada and completed 3 days of testing/training: a 3km track TT on Day 1 and Day 3; and a HIIT session (4-8x, 800m) on Day 2. MC phase was verified by ovulation testing and salivary hormone samples; athletes were classified as either “Low Hormone” or “High Hormone” for analysis. Results: An overall improvement in performance from pre- to post-HIIT TTs occurred (p<0.01). No significant differences in TT performance after HIIT were observed between sexes (p=0.16) or MC phase (p=0.26). Conclusion: These results indicate that competitive XC skiers will likely experience an improvement in TT performance after a bout of HIIT. Coaches and athletes should plan their workouts prior to testing accordingly to maximize TT performance. These results also suggest that no special adjustments need to be considered for differences in performance after HIIT between sexes and MC phase, although further studies with a greater sample size and repeated testing are warranted.

scholarly journals Effects of Active Versus Passive Recovery in Sprint Cross-Country Skiing

2015 ◽  
Vol 10 (5) ◽  
pp. 630-635 ◽  
Author(s):  
Thomas Losnegard ◽  
Martin Andersen ◽  
Matt Spencer ◽  
Jostein Hallén
Keyword(s):  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time Trial ◽  
Oxygen Deficit ◽  
Active Recovery ◽  
Passive Recovery ◽  
Accumulated Oxygen Deficit ◽  
Cross Country Skiing ◽  
Cross Country ◽  
And Performance

Purpose:To investigate the effects of an active and a passive recovery protocol on physiological responses and performance between 2 heats in sprint cross-country skiing.Methods:Ten elite male skiers (22 ± 3 y, 184 ± 4 cm, 79 ± 7 kg) undertook 2 experimental test sessions that both consisted of 2 heats with 25 min between start of the first and second heats. The heats were conducted as an 800-m time trial (6°, >3.5 m/s, ~205 s) and included measurements of oxygen uptake (VO2) and accumulated oxygen deficit. The active recovery trial involved 2 min standing/walking, 16 min jogging (58% ± 5% of VO2peak), and 3 min standing/walking. The passive recovery trial involved 15 min sitting, 3 min walk/jog (~ 30% of VO2peak), and 3 min standing/walking. Blood lactate concentration and heart rate were monitored throughout the recovery periods.Results:The increased 800-m time between heat 1 and heat 2 was trivial after active recovery (effect size [ES] = 0.1, P = .64) and small after passive recovery (ES = 0.4, P = .14). The 1.2% ± 2.1% (mean ± 90% CL) difference between protocols was not significant (ES = 0.3, P = .3). In heat 2, peak and average VO2 was increased after the active recovery protocol.Conclusions:Neither passive recovery nor running at ~58% of VO2peak between 2 heats changed performance significantly.

Aerobic and Anaerobic Contributions to Energy Production Among Junior Male and Female Cross-Country Skiers During Diagonal Skiing

2014 ◽  
Vol 9 (1) ◽  
pp. 32-40 ◽  
Author(s):  
Kerry McGawley ◽  
Hans-Christer Holmberg
Keyword(s):  
Confidence Intervals ◽  
Time Trial ◽  
Mean Difference ◽  
Oxygen Deficit ◽  
Male And Female ◽  
Significant Difference ◽  
The Mean ◽  
Cross Country ◽  
And Performance ◽  
Aerobic And Anaerobic

Purpose:Cross-country-ski races place complex demands on athletes, with events lasting between approximately 3 min and 2 h. The aim of the current study was to compare the aerobic and anaerobic measures derived from a short time trial (TT) between male and female skiers using diagonal cross-country skiing.Methods:Twenty-four highly trained cross-country skiers (12 male and 12 female, age 17.4 ± 1.4 y, body mass 68.2 ± 8.9 kg, height 174 ± 8 cm) participated. The submaximal VO2–speed relationship and VO2max were derived from an incremental ramp test to exhaustion (RAMP), while the accumulated oxygen deficit (AOD), peak VO2, and performance time were measured during a 600-m TT.Results:The female skiers took longer to complete the TT than the males (209 ± 9 s vs 166 ± 7 s, P < .001) and exhibited a lower relative anaerobic contribution (20% ± 4% vs 24% ± 3%, P = .015) and a higher fractional utilization of VO2max (84% ± 4% vs 79% ± 5%, P = .007) than males. Although there was no significant difference in AOD between the sexes (40.9 ± 9.5 and 47.3 ± 7.4 mL/kg for females and males, respectively; P = .079), the mean difference ± 90% confidence intervals of 6.4 ± 6.0 mL/kg reflected a likely practical difference (ES = 0.72). The peak VO2 during the TT was significantly higher than VO2max during the RAMP for all participants combined (62.3 ± 6.8 vs 60.5 ± 7.2 mL · kg−1 · min−1, P = .011), and the mean difference ± 90% confidence intervals of 1.8 ± 1.1 mL · kg−1 · min−1 reflected a possible practical difference (ES = 0.25).Conclusions:These results show that performance and physiological responses to a self-paced TT lasting approximately 3 min differ between sexes. In addition, a TT may provide a valid measure of VO2max.

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