ch7 - age- and sex-related differences and their implications for resistance exercise Flashcards
why should young children strength train?
no evidence of downsides, plus osteogenic benefits of physical activity are essential for skeletal remodeling and growth
what bone area is used to determine biological age?
the left wrist
what is the Tanner method?
visually assessing the development of identifiable secondary sex characteristics
what are the five Tanner classifications?
Stage 1: the immature, preadolescent state, stage 5: full sexual maturation
downsides of Tanner method?
invasive nature of the procedure, should not be used by strength and conditioning professionals
what is the most realistic and feasible means of estimating biological age?
from somatic assessments; somatic age reflects the degree of growth in overall stature or smaller, subdimensions of the body (e.g., limb length).
what are some examples of somatic assessment?
longitudinal growth curve analysis, percentages and predictions of final adult height, and the prediction of age from peak height velocity (PHV), which is defined as the age at maximum rate of growth during the pubertal growth spurt
downsides to peak height velocity?
young athletes may be at an increased risk of injury; age 12 in females and age 14 in males (due to alterations in center of mass, muscle imbalances, and the relative tightening of the muscle-tendon units spanning rapidly growing bones)
how much of the body is muscle mass at birth and adulthood?
at birth, 25% of a child’s body weight; by adulthood, about 40%
when does peak muscle mass occur?
between the ages of 16 and 20 years in females and between 18 and 25 years in males unless affected by resistance exercise / diet
where does the majority of bone formation occur?
in the diaphysis (primary ossification center), which is the central shaft of a long bone, and in the growth cartilage (secondary ossification center), which is located at three sites in the child: the epiphyseal (growth) plate, the joint surface, and the apophyseal insertions of muscle-tendon units (when the epiphyseal plate becomes completely ossified, the long bones stop growing)
at what age are most bones fused?
by the early 20s
why are cartilage injuries devastating?
may disrupt the bone’s blood and nutrient supply and result in permanent growth disturbances (e.g., skeletal undergrowth, skeletal overgrowth, or malalignment of bone)
danger of ligament tears?
may produce an epiphyseal plate fracture in a child
who is more at risk for epiphyseal plate fractures – children or adolescents?
adolescents, due to growth spurt
when do peak gains in strength typically occur in boys?
about 1.2 years after peak height velocity and 0.8 years after peak weight velocity, with body weight being the clearer indicator (also when it occurs in girls but with more variation in relationship of height/bw)
when is peak strength attained?
by age 20 in untrained women and between the ages of 20 and 30 in untrained men
why should a trainer expect a limit to childhood strength gains?
the myelination of many motor neurons is incomplete until sexual maturation (without myelination, fast reactions and skilled movements cannot be successfully performed)
what kind of strength gains can untrained preadolescent children get following short-term (8 to 20 weeks) resistance training programs?
roughly 30% to 40%, variables: biological age of the child, program design, quality of instruction, and background level of physical activity
how permanent are strength gains in children?
impermanent and tend to return to untrained control group values during the detraining period; this finding must be considered in light of the many other commitments that youth or young athletes may have (e.g., competitive playing schedule, schoolwork, time to interact with peers)
benefits of resistance exercise for children?
bone density, favorably alter selected anatomic and psychosocial parameters, reduce injuries in sport and recreational activities, and improve motor skills and sport performancel; decrease in body fat, improvements in insulin sensitivity, and enhanced cardiac function among obese children and adolescents (widespread evidence of a physical inactivity crisis)
why might youth enjoy resistance training?
it is not aerobically taxing and provides an opportunity for all participants to experience success
paradox of sports vs lifting?
the forces placed on the joints of young athletes during sport participation may be far greater, and more difficult to anticipate, than those generated from resistance training programs
men vs women: eccentric strength?
eccentric strength may be more similar between men and women than concentric strength when compared relative to fat-free mass
power output in women relative to men?
about 63% of men’s; similar findings regarding power output were obtained in presumably untrained women; and in maximal vertical jump and standing long jump scores
what kind of short-term gains in hypertrophy are similar between sexes?
up to 16 weeks
broad description of female athlete triad?
interrelationships between energy availability, menstrual function, and bone mineral density from train for prolonged periods of time with insufficient caloric intake
concise description of female triad?
osteoporosis, disordered eating (anorexia/bulimia), amenorrhea (>3 months)
side effects of amenorrhea?
bone stress fractures, endocrine and gastrointestinal complications, and sporting performance decrements
a female middle-distance runner who fails to consume sufficient levels of calcium, vitamin D, and protein may be at what physical risks?
increasing the likelihood of entering into a negative energy balance and experiencing the early onset of female athlete triad
explanations for insufficient energy intake?
lack of a biological drive to match activity-induced energy expenditure, or clinical eating disorders
sports with higher risk of eating disorders?
those with subjective scoring based on aesthetics (e.g., dance or gymnastics)
most significant factor in ACL injury risk in females?
neuromuscular deficiency, which ultimately leads to abnormal biomechanics (increased dynamic knee valgus upon contact with the ground)
how much does competitive weightlifting decline with age?
1% to 1.5% per year until approximately age 70, after which a more dramatic decrease occurs
factors affecting loss of bone with age?
physical inactivity and hormonal, nutritional, mechanical, and genetic factors
explanation for muscle decline after 30?
a decrease in the cross-sectional areas of individual muscles, along with a decrease in muscle density, reductions in tendon compliance, and an increase in intramuscular fat; seems to be most pronounced in women and appears to result from physical inactivity and gradual denervation of muscle fibers.
which decreases more with age – strength or power?
power, due to reduction in fiber size, fiber number and the gradual denervation of muscle fibers
what kind of risk do seniors face from falls?
pain syndromes, joint dislocations, skeletal fractures, limitations on daily functional activities, and a reduction in self-confidence; permanent disability, institutionalization, and fatalities. risk factors include decrements in muscle strength and power, reaction time, and impaired balance and postural stability
significance of activity before (preactivation) and immediately following (cocontraction) contact with the ground?
important mediator of braking and dynamic stabilization in both young and old individuals
how do preactivation and cocontraction work?
preactivation increases stiffness of the limb using fast stretch reflexes to better prepare the limb for ground contact; cocontraction is a motor control strategy that dynamically stabilizes the joint; however, due to the simultaneous activation of both the agonist and antagonist muscle groups crossing the same joint, net joint moments and agonistic force outputs are reduced. seniors rely on increased levels of muscle cocontraction as a compensatory mechanism to offset their increased balance difficulties and to minimize postural sway
how can older adults offset natural reductions in preactivation (wrt: breaking/stabilization)?
low-intensity plyometrics, balance and dynamic stabilization exercises, and proprioception training to develop the ability to react more efficiently with the ground
a coach wants to raise a senior’s activity to prevent falls. why might this be misguided?
seniors must engage with, and adhere to, multidimensional programs that incorporate elements of both resistance and balance training, and seniors should overload progressively to promote a challenging training environment, and training should be completed on a frequent basis to provide individuals with a sufficient training dosage
benefits of strength training in older adults?
gait speed, stair climbing ability, balance, and overall spontaneous activity
resistance training can improve nitrogen retention – why is this significant?
can have a positive effect on muscle protein metabolism
why should valsalva be discouraged in seniors?
the sudden rise in systolic and diastolic blood pressure that the technique creates; especially true for adults with a history of cardiovascular disease (heart arrhythmias, angina) or cerebral conditions (i.e., stroke, dizziness)
rep range/volumes for seniors?
one set of 8 to 12 repetitions at a relatively low intensity (e.g., 40% to 50% 1RM) to higher training volumes and intensities (e.g., three sets per exercise with 60% to 80% of 1RM), depending on needs, goals, and abilities
when can seniors do high-velocity power exercises?
upon completion of a general resistance training program
rep/volume for increasing power in healthy older adults?
one to three sets per exercise with a light to moderate load (40% to 60% 1RM) for 6 to 10 repetitions with high repetition velocity
training frequency for older adults?
twice per week during initial adaptation period, due to recovery length
adolescence
the period between childhood and adulthood
biological age
can be measured in terms of skeletal age, somatic (physique) maturity, or sexual maturation
childhood
period of life before the development of secondary sex
development
the natural progression from prenatal life to adulthood
growth
increase in body size or a particular body part
maturation
the process of becoming mature and fully functional
menarche
menstruation
osteopenia
Osteopenia is defined by a bone mineral density between −1 and −2.5 standard deviations (SD) of the young adult mean
osteoporosis
a bone mineral density below −2.5 SD of the young adult mean. a clinical condition characterized by low bone mass and an increased susceptibility to fractures (as opposed to active bone deterioration, which this could be confused for)
sarcopenia
loss of muscle mass and strength
