This chapter is about the differences between male and females as well as seniors and children. Although most of the research done in the past has been about men and resistance training, women, children and seniors can all benefit from it.

Age- and Sex-Related Differences and Their Implications for Resistance Exercise

• Much of the research that exists today in strength and conditioning is based on the study of adult males. Because there are age and sex related differences, it is important to know how they affect training programs. The chapter begins by defining age and then continues the conversation into sex related differences.
• Resistance Exercise - working against a variety of loads to improve health, fitness and performance.
• Childhood - the time period before children begin to show signs of adulthood. (ex. pubic hair)
• Adolescence - the time between childhood and adulthood.
• Adulthood - fully grown or matured.
• Youth - alternative term for children or adolescents.
• Young Athlete - alternative term for children or adolescents.
• Older - arbitrarily defined as men and women over 65.
• Senior - also arbitrarily defined as men and women over 65.

Children

• The training of youth has recently become a lot more popular. It is important that strength and conditioning professionals understand the fundamental principles of growth and how they affect training. Anatomical, physiological and psychosocial factors that may be associated with acute and chronic injury should all be considered.
• Growth - an increase in body size or body part size.
• Development - the progression from prenatal life to adulthood.
• Maturation - the process of becoming fully mature.
• Puberty - when secondary sex characteristics develop and a child moves into young adulthood.
• It is puberty when we begin to see major differences in body composition and performance.
• Chronological Age - Age in months or in years.
• Biological Age - a better marker for how physically old a person is, determined by measures of skeletal age, changes in physique, or sexual maturation.
• Importantly, there is no scientific evidence that physical training accelerates or delays growth in adequately nourished boys and girls.
• Skeletal age is the gold standard for assessing biological age though, it is expensive to do.
• An alternate method to determine a child's biological age is the Tanner method but, this method should not be used by anyone outside of a qualified clinician as it is highly invasive.
• Menarche - female menstruation.
• Limb length and other calculations can be used to estimate peak height velocity.
• Peak Height Velocity - the age that children grow the fastest. During this time, a child may be at a greater risk for injury. After this age, a child can follow a harder training program.
• Training Age - the amount of time a person has spent resistance training.
• Do not forget to take the psychosocial needs of the athlete into account. Some need help with confidence and motivation.
• Diaphysis - the central shaft of a long bone.
• Growth Cartilage - softer and more flexible than bone, located at three sites in the child. The growth plate, joint surface and apophyseal insertions.
• An important factor in expressing strength is the maturation of the nervous system. This does not occur until sexual maturation. Children should not be expected to respond to training in the same way as adults until they reach full neural maturity.
• Apophyseal - a point where two or more bones join in the spine.
• Mesomorphic - muscular with broad shoulders.
• Endomorphic - rounder with broad hips.
• Ectomorphic - slender and tall.
• It is important that strength and conditioning professionals remember that children are not mini adults.
• Children as young as 5 have benefited from resistance training. Strength gains of roughly 30-40% are typically observed in untrained adolescent children following 8-20 weeks of training.
• Continuous training should be carried out in order to maintain the strength advantage children get from strength training. Some research suggests that this does not affect all children equally.
• The primary gains in strength seen by preadolescent boys and girls are from neurological factors as opposed to hypertrophic factors. It is possible that more advanced measurement techniques may be needed to uncover potential training induced hypertrophy following a program.
• It seems that obese children enjoy resistance training because it is not aerobically taxing and it provides an opportunity for everyone to experience success and feel good about their performance.
• Osteoporosis - low bone mass and an increased likelihood to fractures.
• It seems like late specialization and an involvement in a multitude of sports during the younger years leads to greater success later in age.
• 1-RM testing in children has been proven to be safe if appropriate testing protocols are used.
• Technique, physical awareness, fun and weight room etiquette should be the focus in adolescent programs.

Female Athletes

• Evidence clearly demonstrates that women should follow a resistance training program.
• Before puberty there is virtually no difference in height, weight or size of boys and girls. As puberty hits, this changes drastically.
• Women generally have two-thirds the absolute strength of men. Differences in body composition, dimensions, and muscle mass distribution (women tend to have less above their waist) can explain some of this.
• On a relative basis sex related differences are not as big. Upper body strength is still somewhat less. There is limited data that suggests eccentric strength in women may be more similar than concentric strength in men.
• Muscle quality is not sex specific.
• Female Athlete Triad - the interrelationship between energy availability, menstrual function, and bone mineral density.
• Amenorrhea - the absence of a menstrual cycle for more than three months.
• Since the physiological characteristics of muscle in men and women are the same, there is no sensible reason that resistance training programs for women need to be different. The only real difference is the absolute load used.
• Anterior Cruciate Ligament (ACL) - one of the two ligaments that hold together the knee, the other being the PCL.

Older Adults

• Osteopenia - a bone mineral density between -1 and -2.5 standard deviations from the young adult mean. Low enough to be considered abnormal but, not quite osteoporosis. Related to aging.
• Sarcopenia - loss of muscle mass related to the aging process.
• Preactivation - muscle activity before an exercise.
• Cocontraction - muscle activity that stabilizes joints by activating the agonist and antagonist muscles.
• Resistance training as a standalone does not seem to prevent older adults from falling.
• Aging does not seem to impact the ability of the musculoskeletal system to adapt. You can gain muscle at any age.
• Preexisting medical conditions, training history and nutritional status are all important pieces of information to gather before working with seniors.