Running

Fitness Testing Assignment: Running - by Carolee Hatch

Contents

• Introduction
• Tests of Running Performance
• Anaerobic Tests
• Physical and Physiological Characteristics of Elite Distance Runners
• Conclusion
• References

Introduction

In the quest to improve performance in distance running, much investigation of the variables affecting performance and the protocols for testing such variables has been carried out. Outlined and discussed in this paper are the physiological and physical parameters which identify runners of elite calibre, including oxygen consumption, running economy, body fat, lactate threshold, flexibility and muscle strength.

Tests of Running Performance

Performance in distance running events is dependent on a variety of physiological parameters including maximal and submaximal oxygen consumption, running economy and lactate threshold (Brandon 1995, Tanaka and Swensen 1998).

Much research has stressed the importance of maximal oxyen consumption (VO_{2 max}) as a predictor of endurance running ability. VO_{2 max} is thought to be a function of the pulmonary ventilation and diffusion to oxygenate the blood, cardiac output to transport oxygen to the muscles and mitochondria to extract and process oxygen within the muscle (Lindstedt et al 1988). Superior distance runners are predicted to have VO_{2 max} measures between 75-85ml/kg/min. It appears that VO_{2 max} is more important as a predictor of performance with increases in the distance run (Brandon 1995).

Whilst VO_{2 max} may distinguish elite runners from lesser performers, running economy is important in predicting performance in athletes with homogenous VO_{2 max}. Athletes may have similar VO_{2 max} but dissimilar aerobic demands when running at lesser intensities. Running economy is indicated by submaximal oxygen consumption and is influenced by a variety of factors including percentage body fat, heart rate, temperature, limb mass, dimensions and distribution and differences in weekly mileage and training intensity (Brandon 1995). Morgan and Daniels (1994) found a moderate, positive correlation (r=0.59) between VO_{2 max} and running economy in elite distance runners. In order to predict running performance, useful data would therefore include tests of both maximal and submaximal oxygen consumption.

Recent literature has emphasized the importance of lactate threshold in determining distance running performance. Coetzer et al (1993) investigated the factors related to superior fatigue resistance in black South Africans compared to their white running counterparts and found that VO_{2 max}, running economy and maximal ventilation were not different between the groups but onset of blood lactate was delayed in the black running group. At approximate levels of 4 mmol.l^-1 blood lactate accumulation is said to have commenced. High levels of serum lactate impair aerobic performance, therefore it is desirable for the athlete to delay the onset of lactate accumulation as long as possible (Brandon 1995). The athlete with the ability to delay onset of blood lactate may have superior performance to the athlete with early onset of blood lactate. Trained distance runners would be predicted to begin accumulating blood lactate at intensities of 60 to 90% of VO_{2 max} (Brandon 1995).

Described below are protocols of testing submaximal and maximal oxygen consumption. Lactate testing may be achieved in conjunction with the tests described by blood sampling at various intensities of VO₂ and determining the intensity at which lactate levels exceed 4 mmol.l^-1. In addition, analysis of inspired and expired levels of oxygen and carbon dioxide to determine respiratory quotient will assist in determining anaerobic threshold. Anaerobic threshold is perceived to be the point at which the respiratory quotient exceeds 1.10 (Telford 1991, Brandon 1995).

Submaximal VO₂ Test of Running Economy

The subject runs on a zero degree inclined treadmill beginning at speeds of 12 to 14 kilometers per hour. The subject performs three minute intervals with heart rate and oxygen consumption measured at the two and a half to three minute interval at each speed. The subjects is then given two minutes rest to allow for blood sampling (from the earlobe or finger tip). The treadmill speed is then increased by two kilometers per hour and the test repeated. Ideally the subject will perform at least four speeds. In order to progress to the next stage the subject is asked if he/she can comfortably perform another three minutes at the higher speed. The respiration and comfort of the athlete in the preceding stage should also be considered before advancing the subject to a higher speed. The last stage shou ld be approaching lactate threshold and ellicit lactate responses of 4 to 6 mmol.l^-1 (Telford 1991).

Tests of VO_{2 max}

The maximal extended endurance test is a continuous test at constant velocity. Variables measured include oxygen consumption, respiratory quotient and heart rate. The subject begins running at a velocity of 14 to 16 kilometre per hour for females and 14 to 16 kilometres per hour for males. Every 60 seconds the treadmill gradient is raised by one degree. The subject continues running until maximum heart rate is reached (this may be indicated by exhaustion or failure of the heart rate to increase with increasing velocity) and the respiratory exchange ratio exceeds 1.10. Expected values for females are 50-70 ml.kg^-1.min^-1 and males 55-85 ml.kg^-1.min^-1. Duration of the test is expected to be six to ten minutes with subjects reaching gradients of six to ten per cent (Telford, 1991 ).

Field Tests of Performance and VO_{2 max}

Field tests of VO_{2 max} are used by coaches, when testing multiple subjects is necessary, and when laboratory testing is not practical. Common field tests used are the University of Montreal running track test, the 20 metre shuttle run, the one mile run, the one and a half mile run, and the 12 minute run. Such tests are based on the correlation of increased oxygen uptake with increasing velocity of running (Ahmaidi et al 1992, Kumar Das and Dutta 1995, Van Hazel 1991).

Univerisity of Montreal Test

The test is conducted on a 400 metre track with markers located at every 50 metres of the track. The subject begins running at six kilometres per hour. The velocity is then increased by one point two kilometres per hour every two minutes, paced by sound cues at given intervals played from a pre recorded tape. At each stage the velocity is determined by the distance covered in 30 seconds. The test is ceased when the subject falls five metres short or greater of the designated marker or when the subject feels he/she cannot continue the stage.

VO_{2 max} is determined using the following equation by Ahmaidi et al (1992):

Twenty Metre Shuttle Run

Subjects are organised into groups of two to three to simulate competition and encourage maximal effort. The track is marked with two lines separated by 20 metres. The subject runs at a pace set by a recording on a sound system beginning at a velocity of eight kilometres per hour, increasing by half a kilometre per hour every minute. Subjects complete as many stages as possible. Feedback cues emitted over a sound system are given to assist participants to decide if they can complete the next interval. The test is ceased when the subject feels he/she cannot continue or is unable to reach within three meters of the 20 metre line at the sound cue for the interval on two consectutive occassions. Velocity is determined using covered distance in 30 seconds in the last stage of the test.

VO_{2 max} is determined using the following equation by Ahmaidi et al (1992):

Ahmaidi et al (1992) found no significant difference between VO_{2 max} measured by the University of Montreal Track Test, 20 metre Shuttle Run and treadmill tests of VO_{2 max}. In terms of predicting race velocity however, the 20 metre Shuttle Run was found to be inaccurate at predicting maximal velocity as predictions of maximal velocity were lower for the 20 metre shuttle run than the treadmill or University of Montreal Track Tests.

The twelve minute run, one and one point five mile run have also been shown to correlate highly to VO_{2 max} (Kumar Das and Dutta 1995). Performance may be rated by the time taken to run a specifies distance or distance covered in the time designated as shown below.

(Van Handel 1991)

Anaerobic Tests

Tests of anaerobic ability may also be useful for the distance runner in determining ability to surge and sprint which may be useful in dropping competitors during or at the end of a race. Tests of short sprint speed include time taken for 30 or 40 metre run or maximal distance covered in five to seven seconds which represents use of creatine phosphate and ATP stores (Waibaum and Tschekulyov 1978). Testing of repeated sprint ability is a further option as this may predict ability to repeatedly surge and recover during a race. Fitzsimons et al (1993) advocate the use of a six times 40 metre sprint test with 30 seconds rest between efforts (for distance runners this may be modified by using an active recovery rather than complete rest). Test scoring is time taken for each of the efforts, decrements between time taken for best and subsequent efforts (consistency of effort) and total time taken for the six efforts. Subjects with superior aerobic ability will show high consistency but may have longer total time than subjects with higher anaerobic ability but less ability to maintain sprint efforts (Fitzsimons et al 1993).

Improvements in training will therefore be demonstrated by increased consistency and improved best score per effort (Fitzsimons et al 1993).

Physical and Physiological Characteristics of Elite Distance Runners

Performance in elite distance running may be influenced by physical parameters ie height, body mass, percent body fat and physiological parameters - lactate threshold, maximal heart rate, submaximal and maximal oxygen consumption (Kenney and Hodgson 1985).

Listed below are the physical and physiological characteristics of a group of eight elite male 5000 metre distance runners with mean age 21.4 years (height unknown) and a group of seven 10,000m runners with mean age 23.4 years and height one point eight metres. (Anaerobic Threshold is measured as the oxygen consumption in ml.kg^-1.min^-1 at which lactate accumulation commences and VO_{2 max} is measured in ml.kg^-1.min^-1.

Body Fat

Advantageous to the distance runner are low levels of body fat Body fat may be measured using under water weighing or by skin fold assessment. Recommendations for optimal skin folds for males range from 32 to 42mm when measured at eight sites and for females 40 to 59mm measured from seven sites (Telford 1991). Pereira and Freedson 1997 report that in highly trained male distance runners average percent body fat is of 11.3 per cent which contrasts the normal male population value of 15.7 per cent.

Flexibility

There is debate over optimal levels of flexibility for distance runners. Godges et al (1989) investigated the effect of increasing hip flexibility using static stretches on running economy and submaximal oxygen consumption (submax. VO₂). The effect of stretching was found to be increase submax VO₂ and running economy. In contrast, Craib et al (1996) found that reduced flexibility of the posterior calf and hip rotators correlated with increased running economy in male distance runners.

The proposed positive effects of stretching and increased flexibility on performance are increased balance of muscle and fascia about the pelvis hips, symmetry of the pelvis and correct tensioning of antagonist/agonist relationships (Godges et al 1989). The possible detrimental effects of stretching include loss of stretch shortening or elastic energy recoil of the muscle (Craib et al 1996).

Whilst increased flexibility of the calf and hip external rotators may increase economy in submaximal tasks, increased flexibility may be advantageous for maximal tasks where increased stride rate and length are desirable. The athlete with reduced flexibility may need to use greater muscle action in order to achieve faster velocities than a flexible athlete (Craib et al 1996).

Wang, Whitney, Burdett and Janosky (1993) investigated the flexibility of distance runners and non-athletes. Results indicated that runners had tighter soleus, gastrocnemius and hamstring muscles than non-runners. In contrast no difference was found between rectus femoris and iliopsoas length between groups. Twenty subjects (ten male and ten female) were assessed using goniometric measurement of range of movement. Hamstring length was measured by straight leg raise. Soleus muscle length and gastrocnemius length were measured in prone with the knee flexed for the soleus and extended for the gastrocnemius and the subtalar joint held neutral for both muscle tests. Results for hamstring, gastrocnemius and soleus length are tabulated below.

(Wang et al 1993)

Strength

It is somewhat contrary to expectation that resistance strength training increases performance in endurance running. Weight training is thought to decrease the activity of oxidative enzymes and mitochondrial density and increase muscle fiber size therefore it would be expected that resistance training would be detrimental to aerobic performance.

Resistance training however, whilst found to decrease mitochondrial density has been found to have little effect on levels of oxidative enzymes. Resistance training has the benefits of increasing muscle glycogen stores and enhancing muscle fiber contractile properties which may enhance muscle force generation and increase fatigue resistance (Tanaka and Swensen, 1998).

Muscle Activation During Running

Activation patterns of muscle during the running cycle depend on the incline of the running surface. During running on a flat surface the gastrocnemius and soleus predominantly act to absorb ground reaction forces whilst on small inclines the knee extensors preferentially aborb the shock of foot contact. The posterior calf muscles and hamstrings act concentrically to achieve propulsion up a small incline, however on large gradients quadriceps concentric activity is recruited to propel the athlete forward (Westblad, Svedenhag and Rolf 1996).

During the running gait cycle the quadriceps are active during the first 20% of swing and 50% of stance. Early in swing the hip is flexed by concentric action of the rectus femoris. The rectus femoris simultaneously acts eccentrically at the knee to slow knee flexion. The hamstrings function during late swing to concentrically extend the hip and eccentrically control knee extension (Thordarson 1997).

The posterior calf muscles are active in the last 25% of swing and first 80% of stance and the anterior compartment are active in all of swing and the first 10% of stance. Both anterior and posterior calf act concentrically during the early stance to stabilise the ankle. The posterior calf also function late in stance to propel the body by generating tension of 250% of body weight (Thordarson 1997).

Due to the repeated contractions of the anterior and posterior calf, quadriceps and hamstrings during distance running it may be benefitial to measure the endurance and strength of these muscle groups. Data for concentric and eccentric strength of the aforementioned muscles would be of benefit as eccentric strength will augment concentric activity via the stretch shortening cycle.

Literature suggesting the benefits of eccentric and concentric stength training for endurance running includes Westblad et al (1996) who measured the validity of isokinetic knee extensor endurance measurements in determining running capacity. Eccentric and concentric strength using 100 repeated contractions was found to correlate with VO₂, negatively correlate with blood lactate and positively related to distance running performance. The authors proposed that increased eccentric action in early stance enhances elastic energy potential which augments the propulsive stage of running.

The four simple tests described, provide a basis from which to monitor improvements in individual performance. The results may indicate players appropriateness to a particular position given the position specific energy and anthropometric requirements. Overall, more research is required on a wide range of players with age and skill variation to establish standardised tests and normative data.

Conclusion

There are a myriad of variables determining performance in distance running events including flexibility, muscle strength and endurance, oxygen consumption, running economy, lactate threshold and percentage body fat. Much research has attempted to determine the effect of each of these variables on performance.

Maximal oxygen consumption has been strongly correlated with distance running performance and appears to be an increasingly strong indicator of performance with increasing distance run. Submaximal oxygen consumption and running economy however may distinguish performance in athletes with homogenous VO_{2 max}. Factors affecting economy of running may include percentage body fat and dimensions and relationships of body segments.

Recent research has suggested the importance of lactate threshold as a predictor of performance in athletes with similar oxygen consumption.

Physical and physiological parameter of elite distance runners include low levels of body fat, high VO₂ max, lacate threshold between 60-90% of VO_{2 max} and high running economy.

The importance of flexibility in elite distance runners is unclear with research suggesting that both inflexibility and flexibility may improve performance. Runners have been shown to have reduced flexibility of the posterior calf and hamstrings compared to non runners. Reduced flexibility of the hip external rotators and calf muscles may improve performance by increasing pelvic stability and stretch shortening potential. In contrast, increasing flexibility at the hip may improve performance by increasing muscle balance and relationship between antagonists and agonists during running.

Muscle strength is a further variable that may influence performance in elite runners. Resistance training is known to reduce mitochondrial density and thus would be conceived to reduce distance running performance however improved concentric and eccentric strength of muscle groups used in running has been shown to improve performance by increasing muscle glycogen stores, enhancing muscle contractile properties and increasing fatigue resistance. The activation of muscle groups during running depends on the incline of the running surface. Appropriate testing and strengthening of msucle groups involved in running considering the running surface inclines should be considered in training prescription for distance runners.

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Exercise Physiology Educational Resources 1998