Effect of Cadence on Physiological and Perceptual Responses during Eccentric Cycling at Different Power Outputs.

INTRODUCTION: The effect of cadence in eccentric (ECC) cycling on physiological and perceptual responses is, to date, poorly understood. This study aimed to evaluate the effect of cadence during ECC cycling on muscular activation (EMG), oxygen consumption (V̇O 2 ), and perceived effort (PE) for two different levels of power output. METHODS: Seventeen participants completed four sessions 1 wk apart: 1) determination of the maximal concentric peak power output (PPO) and familiarization with ECC cycling at five cadences (30, 45, 60, 75, and 90 rpm); 2) second familiarization with ECC cycling; 3) and 4) ECC cycling exercise consisting of 5 min at the five different cadences at either 40% or 60% PPO. PE was reported, and V̇O 2 and EMG of seven muscles were calculated over the exercise's last minute. RESULTS: PE, V̇O 2 , and global lower limb muscles activation (EMG ALL ) showed an effect of cadence ( P < 0.001) and followed a curvilinear function. Both low and high cadences increased PE and V̇O 2 responses compared with intermediate cadences. Although muscle activation of vastus lateralis follows a U-shaped curve with cadence, it was greater at low cadence for rectus femoris and biceps femoris, greater at high cadence for tibialis anterior and gastrocnemius medialis, and was not altered for soleus. The estimated optimal cadence was greater (all P < 0.01) for V̇O 2 (64.5 ± 7.9 rpm) than PE (61.7 ± 9.4 rpm) and EMG ALL (55.9 ± 9.3 rpm), but power output had no effect on the optimal cadences. CONCLUSIONS: The physiological and perceptual responses to changes in cadence during ECC cycling followed a U-shaped curve with an optimal cadence depending on the parameter considered.

Cardiorespiratory Changes During Prolonged Downhill Versus Uphill Treadmill Exercise.

Oxygen uptake (V̇O2), heart rate (HR), energy cost (EC) and oxygen pulse are lower during downhill compared to level or uphill locomotion. However, a change in oxygen pulse and EC during prolonged grade exercise is not well documented. This study investigated changes in cardiorespiratory responses and EC during 45-min grade exercises. Nine male healthy volunteers randomly ran at 75% HR reserve during 45-min exercise in a level (+1%), uphill (+15%) or downhill (-15%) condition. V̇O2 , minute ventilation (V̇E ) and end-tidal carbon dioxide (PetCO2) were recorded continuously with 5-min averaging between the 10th and 15th min (T1) and 40th and 45th min (T2). For a similar HR (157±3 bpm), V̇O2 , V̇E , and PetCO2 were lower during downhill compared to level and uphill conditions (p<0.01). V̇O2 and V̇E decreased similarly from T1 to T2 for all conditions (all p<0.01), while PetCO2 decreased only for the downhill condition (p<0.001). Uphill exercise required greater EC compared to level and downhill exercises. EC decreased only during the uphill condition between T1 and T2 (p<0.01). The lowest V̇O2 and EC during downhill exercise compared to uphill and level exercises suggests the involvement of passive elastic structures in force production during downhill. The lower cardiorespiratory response and the reduction in PetCO2 during downhill running exercise, while EC remained constant, suggests an overdrive ventilation pattern likely due to a greater stimulation of efferent neural factors.

Physiological responses during intermittent running exercise differ between outdoor and treadmill running.

The aim of this study was to compare the physiological responses during 15 min of intermittent running consisting of 30 s of high-intensity running exercise at maximal aerobic velocity (MAV) interspersed with 30 s of passive recovery (30-30) performed outdoor versus on a motorized treadmill. Fifteen collegiate physically active males (age, 22 ± 1 years old; body mass, 66 ± 7 kg; stature, 176 ± 06 cm; weekly training volume, 5 ± 2 h·week-1), performed the Fitness Intermittent Test 45-15 to determine maximal oxygen uptake (V̇O2max) and MAV and then completed in random order 3 different training sessions consisting of a 30-s run/30-s rest on an outdoor athletic track (30-30 Track) at MAV; a 30-s run/30-s rest on a treadmill (30-30 Treadmill) at MAV; a 30-s run/30-s rest at MAV+15% (30-30 + 15% MAV Treadmill). Oxygen uptake (V̇O2), time above 90%V̇O2max (t90%V̇O2max), and rating of perceived exertion (RPE) were measured during each training session. We observed a statistical significant underestimation of V̇O2 (53.1 ± 5.4 mL·kg-1·min-1 vs 49.8 ± 6.7 mL·kg-1·min-1, -6.3%, P = 0.012), t90%V̇O2max (8.6% ± 11.5% vs 38.7% ± 32.5%, -77.8%, P = 0.008), RPE (11.4 ± 1.4 vs 16.5 ± 1.7, -31%, P < 0.0001) during the 30-30 Treadmill compared with the same training session performed on track. No statistical differences between 30-30 +15 % MAV Treadmill and 30-30 Track were observed. The present study demonstrates that a 15% increase in running velocity during a high-intensity intermittent treadmill training session is the optimal solution to reach the same physiological responses than an outdoor training session.

Relationship between age and elite marathon race time in world single age records from 5 to 93 years.

BACKGROUND: The aims of the study were (i) to investigate the relationship between elite marathon race times and age in 1-year intervals by using the world single age records in marathon running from 5 to 93 years and (ii) to evaluate the sex difference in elite marathon running performance with advancing age. METHODS: World single age records in marathon running in 1-year intervals for women and men were analysed regarding changes across age for both men and women using linear and non-linear regression analyses for each age for women and men. RESULTS: The relationship between elite marathon race time and age was non-linear (i.e. polynomial regression 4(th) degree) for women and men. The curve was U-shaped where performance improved from 5 to ~20 years. From 5 years to ~15 years, boys and girls performed very similar. Between ~20 and ~35 years, performance was quite linear, but started to decrease at the age of ~35 years in a curvilinear manner with increasing age in both women and men. The sex difference increased non-linearly (i.e. polynomial regression 7(th) degree) from 5 to ~20 years, remained unchanged at ~20 min from ~20 to ~50 years and increased thereafter. The sex difference was lowest (7.5%, 10.5 min) at the age of 49 years. CONCLUSION: Elite marathon race times improved from 5 to ~20 years, remained linear between ~20 and ~35 years, and started to increase at the age of ~35 years in a curvilinear manner with increasing age in both women and men. The sex difference in elite marathon race time increased non-linearly and was lowest at the age of ~49 years.

Comparison of the 45-second/15-second intermittent running field test and the continuous treadmill test.

PURPOSES: To compare the physiological responses and maximal aerobic running velocity (MAV) during an incremental intermittent (45-s run/15-s rest) field test (45-15FIT) vs an incremental continuous treadmill test (TR) and to demonstrate that the MAV obtained during 45-15FIT (MAV45-15) was relevant to elicit a high percentage of maximal oxygen uptake (VO2max) during a 30-s/30-s intermittent training session. METHODS: Oxygen uptake (VO2), heart rate (HR), and lactate concentration ([La]) were measured in 20 subjects during 2 maximal incremental tests and four 15-min intermittent tests. The time spent above 90% and 95% VO2max (t90% and t95% VO2max, respectively) was determined. RESULTS: Maximal physiological parameters were similar during the 45-15FIT and TR tests (VO2max 58.6±5.9 mL·kg(-1)·min(-1) for TR vs 58.5±7.0 mL·kg(-1)·min(-1) for 45-15FIT; HRmax 200±8 beats/min for TR vs 201±7 beats/min for 45-15FIT). MAV45-15 was significantly (P<.001) greater than MAVTR (17.7±1.1 vs 15.6±1.4 km/h). t90% and t95% VO2max during the 30-s/30-s performed at MAVTR were significantly (P<.01) lower than during the 30-s/30-s performed at MAV45-15. Similar VO2 during intermittent tests performed at MAV45-15 and at MAVTR can be obtained by reducing the recovery time or using active recovery. CONCLUSIONS: The results suggested that the 45-15FIT is an accurate field test to determine VO2max and that MAV45-15 can be used during high-intensity intermittent training such as 30-s runs interspersed with 30-s rests (30-s/30-s) to elicit a high percentage of VO2max.

Comparison of the 45s-15s Intermittent Running Field Test and the Continuous Treadmill Test.

PURPOSE: i) to compare the physiological responses and maximal aerobic running velocity (MAV) during an incremental intermittent (45s run/15s rest) field test (45-15FIT) versus an incremental continuous treadmill test (TR); ii) to demonstrate that the MAV obtained during 45-15FIT (MAV45-15) was relevant to elicit a high percentage of maximal oxygen uptake (VO2max) during a 30s-30s intermittent training session. METHODS: Oxygen uptake (VO2), heart rate (HR), and lactate concentration [La] were measured in 20 subjects during two maximal incremental tests and four 15-min intermittent tests. The time spent above 90 and 95% VO2max (t90 and t95% VO2max, respectively) was determined. RESULTS: Maximal physiological parameters were similar during both 45-15FIT and TR test (VO2max: 58.6 ± 5.9 ml.kg-1.min-1 for TR vs 58.5 ± 7.0 ml.kg-1.min-1 for 45-15FIT; HRmax: 200 ± 8 bpm for TR vs 201 ± 7 bpm for 45-15FIT). MAV45-15 was significantly (P<0.001) greater than MAVTR (17.7 ± 1.1 km.h-1 vs 15.6 ± 1.4 km.h-1). t90% VO2max and t95% VO2max during the 30s- 30s performed at MAVTR were significantly (P<0.01) lower compared to the 30s-30s performed at MAV45-15. Similar VO2 during intermittent tests performed at MAV45-15 and at MAVTR, can be obtained by reducing the recovery time or using active recovery. CONCLUSIONS: The present results suggested that the 45-15FIT is an accurate field test to determine VO2max and that MAV45-15 can be used during a high intensity intermittent training such as 30s run interspersed with 30s rest (30s-30s) to elicit a high percentage of VO2max.