Increasing Muscle Mass in High School Athletes

In an attempt to better serve the coaches, players and parents involved in youth and high school baseball, the PBSCCS periodically publishes information on factors that can affect conditioning and performance at these levels. Topics are selected from questions submitted by participants, coaches and parents involved in youth and high school sports.

The question for this posting was from the parent of high school baseball player who said – “My son is 14-years old and 120 pounds. He has a summer birthday making him one of the youngest players on his high school freshman baseball team. His coach told him that he needed to get stronger before his junior year.  How much strength can he expect to gain in this time period?” 

For a response, the PBSCCS contacted Patrick McHenry, MA, CSCS,*D, RSCC who is the Director of Strength and Conditioning at Castle View High School in Castle View, CO and a National Strength and Conditioning Association (NSCA) Board Member for his response.

Muscle mass of a 15-16-year-old boy, on average, is about one-third of body weight versus about 44% of body weight for an adult male. Research shows that the greatest strength gains are between the first semester freshman year and second semester sophomore year in college. My experience indicates that the greatest gains in strength are seen in the second semester of the freshman year for high school males and first semester of sophomore year for college males. Because peak bone mass does not occur until age 21 in many males, loading must be monitored to ensure participant safety. If an athlete does nothing, they will become approximately 3% stronger because of growth.

To answer your question:

·       If a high school athlete has never participated in a structured resistance training program and the coach puts them on a training program, they could see an increase of 50-70 pounds in a year with proper technique.

·       If a high school athlete has participated in a weight a structured resistance training program for 3-4 years, he could see a 20-40-pound increase in a year.

·       Strength gains are larger during and after peak height velocity than before and adaptations to resistance training are greater in adolescent boys during or after peak height velocity1

·       A major limiting factor in strength gain in adolescent males is technique. If an athlete has poor technique, they will plateau between the end of their junior year of high school and start of their senior year.

·       More is not always better. I have frequently seen athletes plateau when they engage in a very heavy lifting program. Some athletes who lift at 90% or more of max in an attempt to make greater gains, often stall. The load is too heavy for them to lift with perfect technique. When lifting weights, it usually comes back to proper lifting technique. Adaptation takes time and optimal gains occur with proper technique.  


1.     Moran, J, et. al. A meta-analysis of maturation-related variation in adolescent boy athletes’ adaptations to short-term resistance training. J Sports Science. 35(11): 1041-1051, 2017.


 Patrick McHenry, MA, CSCS,*D, RSCC, has been the Director of Strength and Conditioning at Castle View High School for 23 years. He is Board Member of the NSCA and a Certified Club Coach with USA Weightlifting. In 2003, he was awarded the Regional Strength Coach of the Year for American Football Monthly, and in 2005 the NSCA High School Strength Coach of the Year. He received the Editorial Excellence Award from the Strength and Conditioning Journal in 2006 and in 2010 his school received one of the first ever Strength of America Awards from the President’s Council on Fitness.





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