Children, Adolescents & Pregnant Clients

Youth Exercise: FITT and Maturation

Children and adolescents are prescribed exercise against the same public-health benchmark used across the lifespan for aerobic activity, scaled to a daily rather than weekly target: at least 60 minutes of moderate-to-vigorous physical activity daily, with vigorous-intensity aerobic activity, muscle-strengthening activity, and bone-strengthening activity each included at least 3 days per week within that daily total. Aerobic work should emphasize variety and play-based activity to sustain engagement; muscle-strengthening can include body-weight exercises, resistance bands, or supervised free-weight/machine training; bone-strengthening activity includes running, jumping, and other activities that produce ground-reaction force.

Resistance-Training Safety Myths

A persistent myth holds that resistance training stunts growth or damages growth plates (epiphyseal plates) in children. Current evidence does not support this: properly supervised, technique-focused resistance training with age-appropriate loads is safe for children and adolescents and does not increase growth-plate injury risk above that of other youth sports; injuries occur primarily from poor technique, excessive load, or inadequate supervision — not from resistance training itself. Youth resistance-training programming follows the same qualitative sequence as adult programming but is more conservative: master technique with body weight or very light external load before adding resistance, use higher-rep low-to-moderate load sets (roughly 6-15 reps), and avoid single-repetition maximum-effort (1-RM) testing before full skeletal maturity; supervision by a qualified professional is essential throughout. Well-designed youth resistance programs improve strength, motor-skill performance, and bone health, and are recommended as part of a well-rounded program rather than avoided.

Maturation

Children of the same chronological age can differ substantially in biological maturation — growth rate, especially around peak height velocity (PHV), is associated with temporarily altered coordination and injury risk as limb length outpaces neuromuscular control. Programming should account for maturational stage (not just chronological age) when selecting technique demands, loads, and progression rate, and should emphasize fundamental movement skills (running, jumping, hopping, balancing, throwing, catching) before sport-specific specialization. Mastering these fundamental movement skills before specialization is also associated with lower overuse-injury rates and better long-term motor competence as children transition into competitive sport.

Thermoregulation in Youth

Children have a higher surface-area-to-body-mass ratio and a less mature sweating response than adults, which slows heat dissipation and heat acclimatization. Youth exercising in hot conditions need more conservative work-to-rest ratios, closer hydration monitoring, and a longer acclimatization period than adult clients performing the same activity (see the environmental section later in this chapter for the general heat-illness framework).

Exercise During Pregnancy (ACOG Guidance)

For clients with an uncomplicated pregnancy who receive clearance from their obstetric provider, ACOG recommends at least 150 minutes per week of moderate-intensity aerobic activity, spread across most days of the week, continuing into the postpartum period. Previously active clients can generally continue their pre-pregnancy routine with the modifications below; previously inactive clients should start gradually.

Key Modifications and Precautions

As pregnancy progresses, the growing uterus shifts the client's center of gravity forward, which — combined with joint laxity from the hormone relaxin — increases fall risk and is part of the rationale for avoiding contact sports and activities with a high risk of falling. Maternal hyperthermia, particularly in the first trimester, has been associated with adverse fetal effects, which is why hot yoga, sauna use, and exercising in high heat/humidity without adequate cooling and hydration are avoided during pregnancy.

Warning Signs to Stop Exercise and Contact the Provider

Vaginal bleeding, regular painful uterine contractions, fluid leaking or gushing from the vagina, dizziness or feeling faint, chest pain, shortness of breath before exertion, headache, and calf pain or swelling are all warning signs requiring the client to stop exercising and contact her obstetric provider immediately. Absolute contraindications to exercise in pregnancy (requiring physician determination) include conditions such as persistent second/third-trimester bleeding, pregnancy-induced hypertension, incompetent cervix, and preterm labor or rupture of membranes; these clients require individualized medical guidance rather than a standard prescription. Relative contraindications — conditions requiring individualized risk/benefit evaluation with the physician rather than an outright stop — include severe anemia, an unevaluated maternal cardiac arrhythmia, chronic bronchitis, poorly controlled type 1 diabetes, and extreme obesity or underweight.

Regular moderate aerobic activity during pregnancy is associated with benefits including reduced risk of excessive gestational weight gain and gestational diabetes, and improved mood, alongside no increase in adverse outcomes when appropriately modified.

Postpartum Return to Exercise

After an uncomplicated vaginal delivery, most clients can gradually resume light activity within days as tolerated and rebuild toward the standard 150-min/week target over several weeks. Clients recovering from a cesarean delivery or other complications should wait for individualized obstetric clearance before resuming structured exercise, and pelvic-floor and core function should be assessed before progressing to high-impact or heavy-loading activity.