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Curtin University
School of Physiotherapy

Strength and fitness evaluations should not be included in a pre-season assessment!

Topic for Summary and Critique - by Linda Kuan

Contents

Statement of the Topic

Strength and fitness evaluations should not be included in a pre-season assessment!

Introduction

In many sports, training for successful competition has become virtually a year-round endeavour. To assist in better preparation, a competitor's year may be divided into off-season and in-season phases, indicating reduced or increased competition commitments, respectively (Koutedakis 1995). The importance of the preseason physical examination and preparticipation evaluation of sports candidates is highlighted because it constitutes one of the few occasions in which the physician can actively prevent sports injuries from occurring (McKeag 1985). This paper discusses the existence of fitness and strength evaluation in a pre-season assessment.

Preseason Assessment

he pre-season assessment can be helpful in planning training, identifying specific problems with regard to individual athletes, developing specific rehabilitation program, assigning protective equipment and identifying individuals who are particularly susceptible to injury (Backus and Reid 1991). Halpern et al (1996) state that specialized fitness evaluation in different sports may aid in detecting deficits in strength and flexibility that may predispose to injury.

Fitness

Fitness encompasses striving for the highest level of existence, including mental, psychological, social, spiritual, and physical components. It is dynamic, multidimensional, and related to heredity, environment, and individual interests. In athletes, physical fitness can be defined as a set of attributes that people have or achieve relating to their ability to perform physical activity, and plays an important role on their performance (Howley and DonFranks 1997).

Components of physical fitness include cardiorespiratory function, relative leanness, flexibility, muscular strength and endurance (Howley and DonFranks 1997). Tests can be conducted in each of these areas:

Cardiorespiratory function

Aerobic fitness test
It can be determined by the maximum oxygen uptake (VO2max), representing the greatest utilization of oxygen in a given time, usually longer than 2 minutes, during exercise (Thoden 1991).
Anaerobic threshold test
Anaerobic threshold represents the workload just below which steady-state exercise can continue for a prolonged time. It can be determined by muscle fiber composition, tissue oxygen diffusion and extraction, mitochondrial density, and the balance of the Krebs' cycle (Koutedakis 1995).
Anaerobic fitness test
Cycle tests, standing board jump and vertical jump tests are used to determined the anaerobic fitness of the athletes (Koutedakis 1995).

Muscle strength and endurance

Sale (1991) defined muscular strength as the peak force (in newtons, N) or torque (in newton-metres, Nm) developed during a maximal voluntary contraction (MVC) under a given set of conditions. Sapega (1990), on the other hand, refers it as the capacity of a muscle for active development of tension, irrespective of the specific conditions under which tension is measured (slow or fast contractile velocity, or shortening or lengthening contraction). Three dynamometry exercise modes are used to measure athlete's strength.

Isometric dynamometry
MVC can be determined against an immovable object, without a change in joint angle, against an unyielding resistance (Sale 1991).
Isoinertial / Isotonic dynamometry
1 repetition maximum (1RM) can be determined by a weightlifting task on a constant external loading (Abernethy et al 1995).
Isokinetic dynamometry
Peak torque can be determined by concentric or eccentric contraction of the limb moving at a constant angular velocity (Sapega 1990). A number of isokinetic devices are commercially available, including the Cybex, Kin-Com, Biodex and Merac systems (Abernethy et al 1995).

Relative leanness

Body girths measurement
Thigh, hip, calf, biceps etc.
Body density measurement
Hydrostatic weighing
Body fat measurement
Skinfold test (Morrow et al 1995)

Flexibility

Sit-and-Reach test

Season Variation in Fitness in Athletes

Flexibility in the lower extremities of 180 male soccer was measured by Ekstrand and Gillquist (1983). They found that players have less flexibility and displayed more muscle tightness in the preseason than in the postseason. Koutedakis et al (1992) studied seasonal deterioration in several physiological variables. Maximal oxygen intake (VO2max) and respiratory anaerobic threshold were measured in 18 international male British skiers. They concluded that seasonal deterioration in aerobic endurance and muscle strength does occur in these athletes. Roemmich and Sinning (1996) studied strength of 8 high school wrestlers in early, mid-, late-, and 3.5-months post-season. A comparison of pre- to late- season demonstrated a lack of lean tissue accretion and reductions in strength. Results of analysis of covariance indicated that lean tissue changes were associated with the changes in strength and power.

Affirmative Argument

Strength as an Indicator of Performance

Muscle strength tests have yielded varying results. Strength tests are most often open chain, single plan, one joint tasks that have little resemblance to sport specific requirements. (Zachazewski 1996).

Blackburn and Morrissey (1998) studied 20 uninjured female subjects performed isotonic strength tests for the knee extensors in OKC and for the hip, knee, and ankle extensors in the squat exercise (CKC). Vertical and standing long jump performance were also assessed. They concluded that lower limb extensor CKC muscle strength was more highly related to jumping performance than knee extensor OKC strength.

Greenberger and Paterno (1995) evaluated the relationship between isokinetic strength of the quadriceps muscle and the performance of a one-legged hop for distance in 20 healthy subjects. It was concluded that isokinetic strength did not correlate strongly with functional tasks.

Ostenberg et al (1998) evaluated isokinetic knee extensor muscle strength at 60 degrees/s and 180 degrees/s and five functional performance tests (one-leg-hop, triple jump, vertical-jump, one-leg-rising and square-hop) in 101 female soccer players. They showed a low correlation between the isokinetic strength measurements and the functional tests and recommended against using isokinetic testing and functional performance testing interchangeably.

Lack of reliability of isokinetic testing

Athletes may have injury in the previous seasons, however, the reliability of strength testing in pathological group remains a possible factor limiting its usefulness. Steiner et al (1993) indicated that test retest reliability of Kin-Com isokinetic dynamometry cannot be the same as in normal individuals as compared with pathological subjects. They investigated test-retest reliability in normals and a group of subjects with tibiofemoral pathologies. The study revealed that subjects with tibiofemoral pathologies had lower reliability values than the healthy subjects.

Strength as predisposing factor for injury

Bennell et al (1998) conducted a study to investigate the relation of hamstring and quadriceps isokinetic muscle strength and imbalance to hamstring injury in 102 senior male Australian Rules footballers. They found no significant differences for any of the isokinetic variables comparing the injured and non-injured legs in players with unilateral hamstring strains. This result concludes that isokinetic muscle strength testing was not able to directly discriminate the risk for hamstring injury.

Flexibility as an Indicator of Performance

Sit-and-reach tests are found on nearly all youth and adult fitness tests because of the perceived relation between performance on these tests and low back pain. However, this relationship has not been well validated. (Jackson et al 1998) A study on 2,747 adults examines the relationship between performance on these two common field tests of muscular strength and flexibility (the sit-up and the sit-and-reach tests) and self-reported low back pain (LBP). The findings did not support the validity of sit-up and sit-and-reach test items for health-related fitness batteries because they were unrelated to LBP.

Relative Leanness as an Indicator of Performance

Rouwmaat et al (1998) assessed the intra- and interexaminer agreement of a manual skinfold thickness test and a manual skinfold compliance test. Twelve healthy subjects were palpated twice in two sessions by 12 examiners. The intra- and interexaminer agreement of the manual skinfold test produced poor-to-fair reliability. The correlation between the examiners' weekly routine and the intraexaminer reliability ranged from low negative to little (if any). This study shows a lack of reliability of palpatory tests for skinfold thickness and skinfold compliance.

Negative Argument

Indicators of Performance

McKeag (1985) supported a pre-season physical examination that included a physical examination, laboratory testing and additional specific screening. These evaluation and injury prediction will aid physicians in preparticipation evaluations.

Feiring and Derscheid (1989) discussed the role of preseason conditioning in injury prevention They supported the view that a preseason physical evaluation should precede this conditioning so that the sports medicine evaluator could assess the athlete's level of conditioning. Based on the strengths and weaknesses of the evaluation a preseason-conditioning program could be devised.

Knapik et al (1991) demonstrated that strength and flexibility imbalances are associated with lower extremity injuries, in 138 female collegiate athletes. Krivickas and Feinberg in 1996 also demonstrated that tight ligaments and muscles are related to injury in 201 college athletes.

Reliability of Dynamometry

Several studies showed high reliability test-retest on the dynamometer in normal population:

Emery et al 1999
Cybex Norm isokinetic dynamometer
Li et al 1996
Cybex 6000 isokinetic dynamometer
Frisiello et al 1994
Biodex isokinetic dynamometer
Snow and Blacklin 1992
Kin-Com Dynamometer

Tripp and Harris (1991) have performed a test-retest reliability study of isokinetic knee extension and flexion torque measurements using subjects with spastic hemiparesis. They concluded that the isokinetic evaluation of torque yielded reliable results in both extremities in this pathological group of patients.

Thompson and Bemben (1999) determined the effectiveness of using accelerometry as a reliable measure of upper body muscular power and its comparability with other conventional measurement tools. Thirty men gave informed written consent before performing a one-repetition maximum (1RM) bench press on a linear bench press apparatus. The results suggested that although minor data acquisition errors were present, accelerometers can provide a reliable and versatile means to assess muscle power.

Indication for injury

Orchard et al (1997) studied 37 professional footballers from an Australian Football League team on preseason measurements of hamstring and quadriceps muscle concentric peak torque at 60, 180, and 300 deg/sec on a Cybex 340 dynamometer. The hamstring muscle injuries that occured during the season were significantly associated with a low hamstring-to-quadriceps muscle peak torque ratio at 60 deg/sec on the injured side and a low hamstring muscle side-to-side peak torque ratio at 60 deg/sec. These results indicated that preseason isokinetic testing of professional Australian Rules footballers can identify players at risk of developing hamstring muscle strains.

Conclusion

Nowadays, the preseason evaluation on both fitness and strength are highlighted in order to prevent injury. However, it remains debatable if these assessments are needed due to the lack of research on both affirmative and negative views. Therefore, more study is required in this area.

References

Abernethy P, Wilson G and Logan P (1995)
Strength and Power Assessment. Issues, Controversies and Challenges. Sports Medicine 19:401-417.
Backus RDH and Reid DC (1991)
Evaluating the health status of the athlete. In MacDougall JD, Wenger HA and Green HJ: Physiological Testing of the High-Performance Athlete (2nd ed). Champaign, Illinois: Human Kinetics, pp 361-402.
Bennell K, Wajswelner H, Lew P, Schall-Riaucour A, Lesile S, Plant D and Cirone J (1998)
Isokinetic strength testing does not predict hamstring injury in Australian Rules Footballers. British Journal of Sports Medicine 32:309-314.
Blackburn JR and Morrissey MC (1998)
The relationship between open and closed kinetic chain strength of the lower limb and jumping performance. Journal of Orthopaedic and Sports Physical Therapy 27:430-435.
Ekstrand J and Gillquist J (1983)
The avoidability of soccer injuries. International Journal of Sports Medicine 4:124-128.
Emery CA, Maitland ME and Meeuwisse WH (1999)
Test-retest reliability of isokinetic hip adductor and flexor muscle strength. Clinical Journal of Sport Medicine 9:79-85.
Feiring DC and Derscheid GL (1989)
The role of preseason conditioning in preventing athletic injuries. Clinical Journal of Sport Medicine 8:361-372.
Frisiello S, Gazaille A, O'Halloran J, Palmer ML and Waugh D (1994)
Test-retest reliability of eccentric peak torque values for shoulder medial and lateral rotation using the Biodex isokinetic dynamometer. Journal of Orthopaedic and Sports Physical Therapy 19:341-344.
Greenberger HB and Paterno MV (1995)
Relationship of knee extensor strength and hopping test performance in the assessment of lower extremity function. Journal of Orthopaedic and Sports Physical Therapy 22:202-206.
Halpern B, Blackburn T, Incremona B and Weintraub S (1996)
Preparticipation Sports Physicals. In Zachazewski JE, Magee DJ and Quillen WS: Athletic Injuries and Rehabilitation. Philadelphia: W.B. Saunders Company, pp 853-868.
Howley ET and DonFranks B (1997)
Health Fitness Instructor's Handbook (3rd ed). Champaign, Illinois: Human Kinetics.
Jackson AW, Morrow JR Jr, Brill PA, Kohl HW 3rd, Gordon NF and Blair SN (1998)
Relations of sit-up and sit-and-reach tests to low back pain in adults. Journal of Orthopaedic and Sports Physical Therapy 27:22-26.
Knapik JJ, Bauman CL, Jones BH, Harris JM and Vaughan L (1991)
Preseason strength and flexibility imbalances associated with athletic injuries in female collegiate athletes. American Journal of Sports Medicine 19:76-81.
Krivickas LS and Feinberg JH (1996)
Lower extremity injuries in college athletes: relation between ligamentous laxity and lower extremity muscle tightness. Archives of Physical Medicine and Rehabilitation 77:1139-1143.
Koutedakis Y, Boreham C, Kabitsis C and Sharp NC (1992)
Seasonal deterioration of selected physiological variables in elite male skiers. International Journal of Sports Medicine 13:548-551.
Koutedakis Y (1995)
Seasonal Variation in Fitness Parameters in Competitive Athletes. Sports Medicine 19:373-392.
Li RC, Wu Y, Maffulli N, Chan KM and Chan JL (1996)
Eccentric and concentric isokinetic knee flexion and extension: a reliability study using the Cybex 6000 dynamometer. British Journal of Sports Medicine 30:156-60.
McKeag DB (1985)
Preseason physical examination for the prevention of sports injuries. Sports Medicine 2:413-431.
Morrow JR, Jackson AW, Disch JG and Mood DP (1995)
Measurement and Evaluation in Human Performance. Champaign, Illinois: Human Kinetics.
Orchard J, Marsden J, Lord S and Garlick D (1997)
Preseason hamstring muscle weakness associated with hamstring muscle injury in Australian footballers. American Journal of Sports Medicine 25:81-85.
Ostenberg A, Roos E, Ekdahl C and Roos H (1998)
Isokinetic knee extensor strength and functional performance in healthy female soccer players. Scandinavian Journal of Medicine and Science in Sports 8:257-264.
Roemmich JN, Sinning WE (1996)
Sport-seasonal changes in body composition, growth, power and strength of adolescent wrestlers. International Journal of Sports Medicine 17:92-99.
Rouwmaat PH, Everaert D, Stappaerts KH and Aufdemkampe G (1998)
Reliability of manual skinfold tests in a healthy male population. Journal of Manipulative Physiological Therapy 21:327-332.
Sale DG (1991)
Testing Strength and Power. In MacDougall JD, Wenger HA and Green HJ: Physiological Testing of the High-Performance Athlete (2nd ed). Champaign, Illinois: Human Kinetics, pp 21-106.
Sapega A (1990)
Current Concepts Review: Muscular Performance Characteristics in Orthpaedic Practices. Journal of Bone and Joint Surgery 72A:1562-1574.
Snow CJ and Blacklin K (1992)
Reliability of knee flexor peak torque measurements from a standardized test protocol on a Kin-Com Dynamometer. Archives of Physical Medicine and Rehabilitation 73:15-22.
Steiner LA, Harris BA and Krebs DE (1993)
Reliability of eccentric isokinetic knee flexion and extension measurements. Archives of Physical Medicine and Rehabilitation 74:1327-1335.
Thoden JS (1991)
Testing Aerobic Power. In MacDougall JD, Wenger HA and Green HJ: Physiological Testing of the High-Performance Athlete (2nd ed). Champaign, Illinois: Human Kinetics, pp 107-173.
Thompson CJ, Bemben MG (1999)
Reliability and comparability of the accelerometer as a measure of muscular power. Medicine and Science in Sports and Exercise 31:897-902.
Tripp EJ and Harris SR (1991)
Test-retest reliability of isokinetic knee extension and flexion torque measurements in persons with spastic hemiparesis. Physical Therapy 71:390-396.

Short Answer Review Questions

  1. Define the terms physical fitness and muscular strength.
  2. Discuss the role of pre-season evaulation.
  3. What are the component of physical fitness tests?
  4. Describe different modes of dynamometery in muscular strength test.
  5. Describe three cardiorespiratory function tests in physical fitness evaluation.

Exercise Physiology Educational Resources 1999