Sedentary Behaviors

From K. Janz

16 hr waking

~ 14 hr waking

Waking Time

80%

4%

16%

SedentaryMVPALight

Children (8-10 yr) Time Spent in Various Activity Intensities Using Accelerometry

Pearce 2012 PlosOne

We are (probably) all trading light timefor sedentary time.

Energy Expenditure (Thermogensis)

Total (TEE) includes resting, thermic effect of food, thermic effect of physical activity (AEE).

Kcal/d (absolute)

Kcal/d average U.S.

Adult 2000 to 3000

4 to 8 y.o 1200 to 1400

14 to 18 y.o. 1400 to 1800

Non-Exercise Activity Thermogenesis

AEE fidgeting, maintain posture, other activities of daily life usually light intensity.

NEAT = AEE that is not purposeful exercise.

College-age male, 75 kg, TEE = 2700 Kcal, 65% REE (1755 Kcal), 10% DEE (270 Kcal), 25% AEE (675 Kcal),

Exercises daily 30 min, 6 METs (.5 hr of circuit training)6 x 75 x .5 = 225 Kcal per day exercise

Example converted from Tremblay

Non-Exercise Activity Thermogenesis

AEE = 675 Kcal = 25% TEEExercise = 225 Kcal (1/3 AEE) Most are NEAT Kcal (2/3 or 450 Kcal)

Need for opportunities for increasing PA levels.

Exercise

Non Exercise

AEE = Kcal/d

Conceptualization and Measurement:Small Decreases Energy Expenditure

• Self-selected walking speed gym shoes = 4 mi/hr (70 kcal/mi)

• Self-selected walking speed flip-flops = 3.6 mi/hr (55 kcal/mi)

• College students 5 mi/d (10,000 steps/d) 15 x 5 = 75

• Theoretically 75 kcal/d from one small change in fashion

• Campus flip-flop season starts early—lasts long time

If 3500 kcal = pound, 1 pound gained in 1.6 months

Calculating Energy Expenditure˙

> 3.5-7 kcal/minmoderate

> 7 kcal/minvigorous

(threshold)

Slopes and linearityof slopes differ via activity.Cross-over walking vs running.

Kcal/min

Summary

Sedentary a Unique Behavior with Unique Antecedents and Health Outcomes

Non Exercise Activity Thermogensis Important All

Less Light Activity Due to Technology

No Solid Evidence Yet of Health Outcomes Effect or Effective Strategies

Strategies to Reduce Sedentary Probably Focus on Increasing Light