Aerobic Conditioning Tidbits


Cross-training may be highly beneficial to overall fitness in the general population. Cross-training tends to have a greater effect on deconditioned individuals as compared to highly trained athletes. However, cross-training may be appropriately implemented to supplement training during periods of injury rehabilitation, overtraining, or psychological fatigue. Also see Specificity of Aerobic Training.

Tanaka H (1994). Effects of cross-training. Transfer of training effects on VO2max between cycling, running and swimming. Sports Med. 18(5): 330-9.

Performance Effects of Environment

The optimum temperature for long distance running performance seems to be around 50-55°F (10-13°C). Performance degrades as much as 2% for every 5°F (2.75°C) above or below this range. High humidity in high temperatures can increase the effective ambient temperature by up to 10°F (5.5°C) by inhibiting evaporation. Direct sunlight can increase the temperature by up to 8-9°F (5°C). Special caution should be advised when the temperature exceeds 80°F (27°C) or relative humidity surpasses 50-60%. See Wind Chill Chart and Heat Humidity Index Chart. Also see Water Requirements.


Capillary osmosis

Oxygen Consumption

A steady state of oxygen uptake can be maintained during prolonged low-intensity exercise. Exercise at a relatively high work rate or in a hot and humid environment results in an upward drift in oxygen consumption over time, so a steady state is not obtained under these circumstances. During incremental (graded) exercise, oxygen uptake increases linearly until VO2 max is reached.

Fat Metabolism & Aerobic Intensity

The total rate of fat oxidation during exercise is greatest at higher intensities that are below the lactate threshold. For example, during exercise at 20% of VO2 max, approximately 60% of the energy would come from fat. By comparison, exercise at 50% of VO2 max, only about 40% of the energy would come from fat. Nonetheless, the absolute amount of fat metabolism is 33% higher during exercise at 50% VO2 max since the total energy expenditure is 250% greater than exercising at only 20% of VO2 max. The greatest absolute fat metabolism during exercise occurs at 50% of VO2 max in untrained subjects (body weight: 89 kg; VO2 max: 4.0 L/min; lactate threshold: 60% of VO2 max).

Lactate Threshold

Lactate threshold (controversy AKA anaerobic threshold) is the point at which blood lactic acid rises systematically during graded exercise. Lactate threshold occurs in untrained subjects around 50-60% of VO2 Max and in trained subjects around 65-80% of VO2 Max. Lactate threshold can be used as a marker of training intensity. It can also be used in combination with other physiological measurements, such as VO2 max, as a predictor of long-distance running performance (Farrel P, et al. 1979; Marti B, Abelin T, Howald H, 1887).

Progression and Recovery

After a hard workout, take a day off or have an easy workout. Increase your weekly distance by no more than 10 percent. After a few weeks of distance increases, drop distance by 50 percent for one week. Occasionally, reduce your weekly distance by 10-15 percent, while increasing your pace by 6 to 12 seconds per kilometer (10 to 20 seconds per mile).

Elliptical Cross Trainer

Precor Elliptical (EFX) Distance Conversions

Strides Miles Km
560 0.25 0.4
1120 0.5 0.8
1680 0.75 1.21
2241 1 1.61
3361 1.5 2.41
4482 2 3.22

See Elliptical Trainer and Elliptical Cross Trainer.


You burn 7% fewer calories for every 10 pounds (4.5 kg) of weight you lean on the handrail of a stair climbing machine. (typical 143 lb person x 7% = 10 lbs)

Outdoor vs Treadmill Running

The Aerobic demand for outdoor running at 5 m/s is 5% to 7% higher than that for treadmill running.

Jones AM, Doust JHA (1996). 1% treadmill grade most accurately reflects the energetic cost of outdoor running. J Sports Sci. 14; 321-327.

Row Ergometer

Concept II Rower (2500 Meter Records):

  • Men: 7:10.7
  • Women: 8:12.5


Group Exercise Music - Beats per Minute (BPM)

Class BPM
Floor work / Muscular conditioning 115-135
Step 120-128
Interval 120-128
Slide 120-130
Cycling 124-130
Hi/Lo 135-160


Shoe wear: standard, pronate, supinate

Purchasing Shoes

Your feet are not identical, so fit the larger one when buying shoes. The best time of day to shop for a shoe is at the end of the day, when your foot is the largest. A long jog in warm weather can expand a runner's feet as much as half a size. Test shoes before you buy them. Good shoes should feel comfortable when you first try them on, not after they have been broken in. Buy new running shoes every 240 to 450 miles (400 to 725 km). Buy new walking shoes every 400 hours of use (eg: after 40 weeks of 10 hours of walking per week). Many models of running shoes are now specially designed for those who pronate as well as those with a standard gait.

  • Left: Standard
  • Middle: Pronate
  • Right: Supinate

Average Marathon Times in US (2005)

  • Men: 4 hours 32 minutes 8 seconds
  • Women: 5 hours 6 minutes 8 seconds

Marathon World Records

  • Men: 2:3:59, Haile Gebrselassie (Ethiopia), Berlin Marathon, Sept 28, 2008
    • average pace: <2:57 per kilometer (4:44 per mile)
    • average speed >20.4 km/h (12.6 min/hr)
  • Women: 2:15:25, Paula Radcliffe (Great Britain), London Marathon, April 13, 2003

Walking the USA

In 1909, Edward Payson Weston walked 3,795 miles from New York to San Francisco in 104 days and 7 hours. Along the way, he endured many obstacles such as heavy blizzards. At the time, he was celebrating his 70th birthday.

The following year Weston walked back to New York from Los Angeles. He completed the 3,600 mile trek in 76 days and 23 hours.

Older Runners

Running and Pain After 50

Runners 50 years of age or older suffer 25 percent less musculoskeletal pain than their peers who do not run.

B Fries, JF Fries, DP Lubeck (2005). Aerobic exercise and its impact on musculoskeletal pain in older adults. Arthritis Research and Therapy, 6(7): 1263-70.

Decline in Aerobic Endurance

Entering the second half of life, the average adult loses 1.5 percent of aerobic capacity per year (Cooper 2007).

Problems with Traditional Swim Training


Exercise physiologist Dave Costill remarks:

  • 'Most competitive swimming events last less than two minutes. How can training for 3 to 4 hours per day at speeds that are markedly slower than competitive pace prepare the swimmer for the maximal efforts of competition?'
  • '...large training volume prepares the athlete to tolerate a high volume of training, but likely does little to benefit actual performance'

Also see

Tall Swimmers

Swimmers who have better performance tend to be tall, have higher surface areas, and better stroke mechanics.

Jorge E Morais, Nuno D Garrido, Mário C Marques, António J Silva, Daniel A Marinho, Tiago M Barbosa (2013). The influence of anthropometric, kinematic and energetic variables and gender on swimming performance in youth athletes. J Hum Kinet. 203-11

Circulation Diagram

Vascular Dimensions
  • The aorta, one of the largest arteries in the body, is the diameter of a garden hose.
  • In contrast, ten capillaries are equal to the thickness of a single human hair.
  • The human body contains about 6 quarts of blood, which circulate through the body three times every minute.
  • Each day, the blood travels about a total of 12,000 miles (19,300 km) per day (4 times across the US from coast to coast).
  • In a lifetime, the human heart will pump about 1 million barrels of blood - enough to fill over 3 super-tankers!


Diagram of the Organs of the Circulation

  • L: pulmonary circulation
  • M: circulation through the organs suspended by the mesentery
  • P: circulation through the liver
  • The circulation through other organs, such as brain, muscles, skin, and kidneys, is indicated.
  • Lymphatics are represented by dotted lines.

Heart Volumes (ml)

  Male Female
Athlete 860 725
Non-Athletic 670 580

Heart Pump / Machine Pump

Heart Pump

Mechanical Pump

Red Blood Cells in Capillaries

A Horse's Dynamic Red Blood Cells

In the horse, circulating hemoglobin concentration doubles from rest to maximum exercise. This great augmentation of oxygen delivery to the working muscles, presumably accounts in part for that species' remarkably high VO2 max (approximately 160 ml/kg/min). This is 3 to 4 times higher than in a fit healthy human. In humans, there is virtually no contribution to the increase in VO2 by hemoglobin concentration changes from rest to exercise.

Wagner PD, (1991) Central and peripheral aspects of oxygen transport and adaptations with exercise, Sports Medicine, 11 (3): 133-142

Oxygen Consumption of Organs

Organ O2 Consumption
Heart 11.6 %
Brain 18.4 %
Liver 20.4 %
Muscle ~ 20 %

During intense exercise, oxygen demand may increase to up to 15 times resting requirements.

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