Predictors of Running Performance
Peak running speed is a better predictor of running performance (e.g. marathon time) than is either VO2 max or the running economy. Lactate turnpoint and respiratory ventilation threshold (a.k.a. anaerobic threshold) are other variable that accurately predict athletic performance, particularly in running events of 10 to 42 km.
Noakes TD (1988). Implications of exercise testing for prediction of athletic performance, a contemporary perspective, Medicine and Science in Sports and Exercise. 20 (4): 319-330.
Inverted T wave with strong QRS voltage is also normal in athlete's. Up to 10% of trained athletes may exhibit 2nd degree heart block
Houston TP, Puffer JC, Rodney WM (1985). The Athletic Heart Syndrome, N Eng J Med. 313 (1): 24-32.
Many arrhythmias observed in athletes can be considered normal for this population and are not related to any pathology. Several of these rhythm and electrocardiographic changes seen in aerobic athletes at rest resolve during exercise. Routine screening for cardiovascular artery disease for asymptomatic athletes is not recommended due to the high rate of false positives. If the athlete is able to exercise at maximal intensity without difficulty, it can be concluded that abnormal ECG changes are likely attributed to the Athletic Heart Syndrome.
Crown LA, Hizon JW, Rodney WM (1997). The Athlete's Heart, The Team Physician's Handbook, Mosby, 2: 294-303.
Hypertension (high blood pressure) is only a risk factor for cardiovascular disease and not necesarily considered a Cardiovascular Disease in itself (see Modified ACSM Risk Classification Form), particularly since 95% of diagnosed hypertension is idiopathic (no known cause). It is also known as Essential or Primary Hypertension. Essential Hypertension is likely caused by and interaction between genetic and environmental factors. Also see Vitals Calculator.
VO2 max Differences
The aerobic capacity of women is typically about 10-20% less than men (Astrand, 1977).
VO2 max steadily increases during childhood and reaches a peak at around the age of 20, after which, it slowly declines.
The VO2 max of a highly trained endurance athlete is about twice that of an average person.
VO2 max Estimate Inaccuracies
An overestimation of VO2 max can result from failure to achieve steady state or rail holding during treadmill testing. Other inaccuracies can result from improperly calibrated ergometers and factors that change mechanical efficiency such as wind, snow, sand, and gait abnormalities.
In utero (prenatal), androgen exposure is inversely related with 2D:4D ratio. Other factors where 2D:4D ratios also appears to be negatively correlated with certain components of fitness:
- Hand grip strength in men only
- Endurance Running (accounts for 25% of variance)
- Muscle mass and strength in older adults (73.72 ± 6.23 years of age).
Halil M, Gurel EI, Kuyumcu ME, Karaismailoglu S, Yesil Y, Ozturk ZA, Yavuz BB, Cankurtaran M, Ariogul S (2013). Digit (2D:4D) ratio is associated with muscle mass (MM) and strength (MS) in older adults: possible effect of in utero androgen exposure. Arch Gerontol Geriatr. 56(2):3 58-63.
Hone LSE, McCollough E (2012). 2D:4D ratios predict hand grip strength (but not hand grip endurance) in men (but not in women). Evolution & Human Behavior. 33(6): 780-789.
Manning JT1, Morris L, Caswell N (2007). Endurance running and digit ratio (2D:4D): implications for fetal testosterone effects on running speed and vascular health. Am J Hum Biol. 19(3): 416-21.
Black Women & Heart Disease
Compared to white women, black women have a higher incidence of heart disease and they are twice as likely to die from the disease.
Racial and Ethnic Discrepancy in Pulse Oximetry
Pulse oximeter overestimated blood-oxygen saturation by an average of 1.7 percent for Asian individuals, 1.2 percent for Black individuals, and 1.1 percent for Hispanic Individuals since the technology and statistical model to estimate arterial blood-gas measurements are standardized for those with a light complexion.
Fawzy A, Wu TD, Wang K, Robinson ML, Farha J, Amanda Bradke A, Golden SH, Xu Y, Garibaldi BT (2022). Racial and Ethnic Discrepancy in Pulse Oximetry and Delayed Identification of Treatment Eligibility Among Patients With COVID-19. JAMA Intern Med. 182(7): 730–738.
Precordial Cordial Catch Syndrome
A common chest pain is Precordial Cordial Catch Syndrome. It's a random stabbing chest pain localized to an intercostals space along the left lower sternal border or to the cardiac apex. It can be made worse with deep inspiration. Unlike Angina pectoris, it's not is not life threatning. Although the underline cause of this condition is unknown, it's suspected to be caused by a piched nerve across chest wall.
Giraffes have the highest blood pressure at 280/180 mm Hg.
Old-time Youth Pushups
It's remarkable how little fitness is required to be considered 'average' nowadays. See girl's push-ups norms. In 1945, a score 32 repetitions for high school girls push-ups was only 60th percentile. Keep in mind, girls push-ups were with the knees straight (sometimes performed holding on to a 13" high stall bar bench) lowering the body until the chest nearly touched. Interestingly, the boy's push-ups were described as what we call dips performed on parallel bars.
Metheny E (1945). Physical performance levels for high school girls, Journal of Health and Physical Education. 16:84.
Willgoose CE (1961) Evaluation in Health Education and Physical Education, McGraw-Hill Book Company, Inc. 136-137.
| 1 Kilopond-meter (kpm) = kgm
1 kcal = 426.8 kpm
1 Joule (J) = 0.101 kgm
| 1 Watt = 6.12 kpm/min = 1 J/sec
1 kpm/min = 0.163 Watts
ExRx.net Calculator Results
The results of ExRx.net calculators can be copied and pasted into an e-mail or document and presented to others for exercise testing and prescription. Alternatively, the results can be printed directly from the ExRx.net and can be given to the individual. A copy can also be kept with the individual's raw data, (e.g. fitness testing sheet) for future reference. The entire contents of the ExRx.net web site is also available on for off-line use (See ExRx.net Offline Download).