dynamometry (maximal strength), and isokinetic
equipment (60 to 120°/s).- Muscular endurance can be measured by maximal
number of push-ups, pull-ups, and/or sit-ups, as well
as hand grip dynamometry (sustained submaximal
endurance), and isokinetic equipment (180 to
300 °/s).
REFERENCES
Demirel HA, Powers SK, Naito H, et al: Exercise-induced alera-
tions in skeletal muscle myosin heavy chain phenotype: Dose-
response relationship. J Appl Physiol86(3):1002–1008, 1999.
Gaesser GA, Poole DC: The slow component of oxygen uptake
kinetics in humans, in Holloszy JO (ed.): Exercise and Sport
Science Reviews, vol. 24. Baltimore, MD, Williams & Wilkins,
1996, p. 35.
Pette D, Staron RS: Transitions of muscle fiber phenotypic pro-
files. Histochem Cell Biol115:359–372, 2001.
Poole DC, Richardson RS: Determinants of oxygen uptake:
Implications for exercise testing. Sports Med 24:308–320, 1997.
Staron RS: Human skeletal muscle fiber types: Delineation, devel-
opment, and distribution. Can J Appl Physiol22:307–327,
1997.
Tanaka H, Monahan KD, Seals DR: Age-predicted maximal heart
rate revisited. J Am Coll Cardiol 37:153–156, 2001.
Zhen-He H, Bottinelli R, Pelligrino MA, et al: ATP consumption
and efficiency of human single muscle fibers with different
myosin isoform composition. Biophys J79:945–961, 2000.
BIBLIOGRAPHY
American College of Sports Medicine: Guidelines for Exercise
Testing and Prescription, 6th ed. Baltimore, MD, Lippincott
William & Wilkins, 2000.
Astrand P-O, Rodahl K, Dahl HA, Stromme SB: Textbook of
Work Physiology: Physiological Bases of Exercise, 4th ed.
Champaign IL, Human Kinetics, 2003.
ATS/ACCP: Statement on cardiopulmonary exercise testing. Am
J Respir Crit Care Med167:211–277, 2003.
Billat LV: Use of blood lactate measurements for prediction of
exercise performance and for control of training. Sports Med
22:157–175, 1996.
Campos GE, Luecke TJ, Wendeln HK, et al: Muscular adaptations
in response to three different resistance training regimens:
Specificity of repetition maximum training zones. Eur J Appl
Physiol88:50–60, 2002.
McArdle WD, Katch FI, Katch VL: Exercise Physiology: Energy,
Nutrition, and Human Performance,5th ed. Baltimore, MD,
Lippincott, Williams & Wilkins, 2001.
McHugh MP, Tyler TF, Greenberg SC, et al: Differences in acti-
vation patterns between eccentric and concentric quadriceps
contractions. J Sports Sci20:83–91, 2002.
Rodriguez LP, Lopez-Rego J, Calbet JA, et al: Effects of training
status on fibers of the musculus vastus lateralis in professional
road cyclists. Am J Phys Med Rehabil81:651–660, 2002.
Wasserman K, Hansen JE, Sue DY, et al: Principles of Exercise
Testing and Interpretation: Including Pathophysiology and
Clinical Applications, 3rd ed. Baltimore, MD, Lippincott,
Williams & Wilkins, 1999.9 ARTICULAR CARTILAGE INJURY
Stephen J Lee, BA
Brian J Cole, MD, MBAINTRODUCTION- Articular cartilage lines the articulating surfaces of
diarthrodial joints and serves several important func-
tions: (1) provision of a smooth, low-friction surface,
(2) joint lubrication, and (3) stress distribution with
load bearing. - Articular cartilage injury most commonly occurs in the
knee and thus has been most extensively studied in this
area. Cartilage injuries of the knee affect approxi-
mately 900,000 Americans annually, resulting in more
than 200,000 surgical procedures each year to treat
high-grade lesions (grade III or IV) (Cole et al, 1999). - In a restrospective study of 31,516 knee arthroscopies,
Curl and associates (1997) identified articular cartilage
damage in 63% of the patients. Among those affected,
41% had grade III and 19% grade IV lesions. More
recently, Hjelle and colleagues (2002) prospectively
evaluated 1000 knee arthroscopies and found chondral
or osteochondral defects in 61% of the patients with
55% of the defects classified as grade III and 5% grade
IV. The weight-bearing zone of the medial femoral
condyle was found to be the most commonly affected
area (58% of all articular cartilage lesions). Other
commonly affected areas include the weight-bearing
zone of the lateral femoral condyle and patellofemoral
joint (Hjelle et al, 2002; Brittberg, 2000).
COMPOSITION AND ORGANIZATION- Articular cartilage consists primarily of a large extra-
cellular matrix(ECM) and a sparse population of
chondrocytes.
46 SECTION 1 • GENERAL CONSIDERATIONS IN SPORTS MEDICINE