The Energy Contributions?Energy Cost And Maximal Lactate Steady State Characteristics Reasearch In Elite Wheelchair Racers

Wheelchair racing derived from sports for rehabilitation of World War II veterans.In 1964,the sport was included as a formal event of the Paralympics,and has developed into one of the most prominent sports among the disabled community.Participants of this sport mainly include two categories:The first is athletes with spinal cord injury,physical disability,and post-polio syndrome?T5i,i.e.,i=1,2,3,4,including spinal cord injury of level c5-6,c7-8,t1-7,and t8-s4?;the second is those with cerebral palsy?T3i,i.e.,i=levels 3 and 4,including Spastic,Ataxic,and Athetoid?.Wheelchair racing is a periodic physical fitness event which mainly involves the movement of upper limbs.Athletes of this sport are usually with problems such as lower limb dysfunction,muscular atrophy,spinal cord injury,and disorders of nerve coordination and control.It has to be played with a wheelchair and is highly-demanding for aerobic capacity.According to previous studies,different water and land sports vary significantly in energy cost?C?.Energy cost?C?is critical to the performance of cyclic sports activities,and is therefore used by coaches as a major reference in making scientific training and dietary plans for their trainees.Chinese coaches and researchers'understanding of energy contributions for wheelchair racing of different distances is mainly based on the early research of Astrand et al.?1970?on large muscle groups engaging in high-intensity movements.However,no direct research has been conducted on wheelchair racing energy contributions and energy cost.Maximal lactate steady state?MLSS?is the highest lactate concentration and workload that can be maintained over time without a continual blood lactate accumulation.It is the main physiological determiner for aerobic training intensity.MLSS varies according to the muscles engaged in different sports.However,coaches in China still set the intensity of endurance training according to the MLSS of running.Objective:This study approaches wheelchair racing from three key indicators,namely,energy contributions,energy cost and maximal lactate steady state.We hope coaches will find our findings useful as they make scientific training and dietary plans for athletes.Method:?1?Wheelchair racing Energy contributions research Ten professional male wheelchair racers?Age:22.90±5.17yrs,Sitting height:90.90±3.21cm,Weight:59.27±8.31 kg,Training Time:4.00±2.74 years?were recruited to complete one incremental test and six all-out trials?Distance:100 m,200 m,400m,800m,1500m,and 5000m?,all racers using their own racing wheelchair for tests.A K4b²portable gas analyzer,a Polar heart rate belt and an EFK blood lactate analyzer were used to monitor the racers'VO₂ at every breath,heart rate and blood lactate concentrations changes.Data was calculated with both the MAOD and PCr-La-O₂methods and the results were compared.?2?Wheelchair racing energy cost research Ten professional athletes for Class T54 men's wheelchair racing?Age:22.90±5.17yrs,Sitting height:90.90±3.21 cm,Weight:59.27±8.31 kg,Training Time:4.00±2.74 years?were recruited to complete a 1500m all-out test and an incremental test.,all racers using their own racing wheelchair for tests.A portable gas analyzer,EFK blood lactate analyzer,a GPSports and a Polar heart rate belt were used to measure VO₂ at every breath,lood lactate concentrations,speed and heart rate changes of the athletes.?3?Wheelchair racing maximal lactate steady state research Maximal lactate steady state?MLSS?is the highest lactate concentration and workload that can be maintained over time without a continual blood lactate accumulation.It is the main physiological determiner for aerobic training intensity.MLSS varies according to the muscles engaged in different sports.However,coaches in China still set the intensity of endurance training according to the MLSS of running.This study aims to measure the MLSS of athletes in Class T53/T54 wheelchair racing and set a proper standard of aerobic training intensity for the athletes.Result:?1?Wheelchair racing Energy contributions research The anaerobic energy contributions of wheelchair racing of distances varying from 100 m to 5000 m was 11.30±3.57 KJ,20.78±11.89 KJ,37.95-45.40 KJ,43.52-53.36 KJ,58.37-59.23 KJ,and 53.49-104.74 KJ,respectively.The corresponding aerobic energy contributions was3.02±1.28 KJ,7.11±2.75 KJ,19.84±6.23 KJ,65.46±18.93 KJ,127.14±26.00 KJ,and535.95±76.14 KJ,respectively.The MAOD results of anaerobic and total energy contributions were mostly lower than those produced by the PCr-La-O₂ method?especially in 400 m,p<0.05?.As a result,the relative aerobic energy contributions(W_AER%)was higher under the MAOD method than the PCr-La-O₂ method.?2?Wheelchair racing energy cost research At the 1500m all-out test,the racing speed was 7.20±0.28 m/s and C_w was 0.13 KJ/m;at the incremental test,the C_w gradually increased from 0.09 KJ/m to 0.12±0.02 KJ/m,as speed increased from5.38±0.25 m/s to 6.45±0.29 m/s.The C_w-speed and VO₂-speed regression equation was C_w=0.059x¹.6175.6175 and VO₂=379.2x^1.8705,respectively.?3?Wheelchair racing maximal lactate steady state research The blood lactate value at MLSS of Class T53/54 Wheelchair Racing was 5.3±1.0 mM.The measured MLSS speed?23.89±1.22 km/h?was significant higher than the incremental test of 4mM?23.07±1.07 km/h,p<0.05?,similar with the incremental test of 5 mM?23.64±1.85km/h,p>0.05??5.3 mM?23.87±1.86 km/h,p>0.05?.Conclusion:?1?Wheelchair racing energy contributions of the 100 m,200 m and400 m races is mainly anaerobic,that of 800 m race is both aerobic and anaerobic,and that of the 1500 m and 5000 m races is mainly aerobic.The indicators of athletes participating in Class T54 wheelchair racing can serve as an important physiology reference for coaches to make training plans,explore different energy supply systems,and evaluate sporting abilities.?2?This study has also proved that different calculation methods are the cause of W_AER%difference.The MAOD method leads to overestimation of W_AER%,especially in the 400 m race.Coaches and researchers need to make choices according to their needs in practical application.?3?The C_w and VO₂ of wheelchair racing increase with speed in an exponential trend.Wheelchair racing features high percentage of aerodynamic resistance,low percentage of non-aerodynamic,and low proportion of muscles not involved in energy conduction.In such a context,the energy cost of wheelchair racing is significantly different from that of able-bodied people's walking,running,riding,swimming and rowing,and is close to that of speed skating.?4?The MLSS level for Class T53/54 wheelchair racers is significant higher than4 mM Lactate Threshold,recommend to use 5.3 mM as T53/54 Wheelchair Racing events Lactate Threshold,for aerobic training intensity standard.