Don't use heavy weights yet! Teens should start out with lighter weights, proper form, and more repetitions. A good rule of thumb is to start with a weight you can easily lift 10 times, with the last two repetitions being increasingly difficult. For some teens, this might be 1 pound to 2 pounds.
As a general rule, it's important to start with lighter weights and gradually increase as your strength and fitness improves. For most 14-year-olds, a good starting weight for dumbbells is around 5-10 pounds (2.5-5kg) per hand.
14-15 Years Old
At the age of 14 to 15, teenagers are just starting to physically mature. As such, the average deadlift for this age group is typically around 100-135 pounds for boys and 75-100 pounds for girls. However, these figures should not be seen as a hard and fast rule.
Doctors and physical therapists recommend that kids carry no more than 10% to 20% of their body weight in their packs. But many carry a lot more than that.
The best age for teenagers to start lifting dumbbells can vary depending on the individual, but generally, many experts recommend that teenagers can begin strength training around the age of 13 or 14. At this age, teenagers are typically physically mature enough to handle basic strength training safely and effectively.
Many 14-year-old boys experience growth spurts during puberty and can build muscle through weight training. However, since their skeletal system is still developing, they need to be careful to avoid injury.
If your child is around 14-15 years, they may think of joining the gym for functional exercises, jumping, skipping, sit-ups, cycling, running, aerobics, yoga, pilates or kickboxing. They should avoid high-intensity or vigorous exercises as they may lead to injury, sprains or stains.
For a 14-year-old, the average bench press is typically around 65 pounds. For a 15-year-old, the average is around 85 pounds. For a 16-year-old, the average is around 100 pounds. For a 17-year-old, the average is around 115 pounds.
Medium vs. Heavy Weights. For beginners, Ben recommends trying five to 10 pounds for light weights, 10 to 20 pounds for medium weights, and 15 to 30 pounds for heavy weights—or simply starting with five-pound weights for each exercise and working up from there.
In general, a 225-pound deadlift is a significant accomplishment for anyone, regardless of age or weight. For a 14-year-old, it is especially impressive and may indicate that they have been consistently engaging in strength training.
"There's no evidence that weightlifting stunts growth", she said. "In fact, resistance training can help build coordination and strength in young athletes, and there's a strong push right now for young female athletes to lift weights in the hope that it may offer more injury prevention.
For best results, do strength exercises for at least 20–30 minutes 2 or 3 days per week. Take at least a day off between sessions. Work the major muscle groups of your arms, legs, and core (abdominal muscles, back, and buttocks). Strength training is just one part of a balanced exercise routine.
Lifting too much weight can injure tendons and cartilage, including the growth plates -- it's likely that this is where the myth of weightlifting stunting growth has come from. While avoiding injury is important, it's worth noting that these injuries are highly unlikely to be permanent and will not stunt growth.
A good rule of thumb is to start with a weight you can easily lift 10 times, with the last two repetitions being increasingly difficult. For some teens, this might be 1 pound to 2 pounds. If you are strong and fit, you might start at 15 pounds to 20 pounds.
That's your one rep max (1RM) – the peak weight you can handle for a single lift, be it a squat, bench press, deadlift, or any other exercise.
Mid-parental method
Another way to estimate your child's adult height is to add together the height of both parents and divide it by two. Then, some methods say to add 5 inches if they're a boy and subtract 5 inches if they're a girl; others say to only add or subtract 2 ½ inches.
Both scenarios are normal. Keep in mind, however, that you may not see bulky muscles until your body develops further, because bulking up is dependent on higher levels of the hormone called testosterone. That's why it's very unusual to see a 14-year-old with abs.
Many clubs also require that members aged 14 must be accompanied by a parent/guardian at all times. Members who are 15-17 years old (15-18 in regions where 19 is the age of majority) must have a signed waiver from a parent or guardian.
Strength training does not stunt growth…. however, maximal lifting (highest weight amount you can lift one to three times) may put you at more risk for injury to the growing areas of a child's body. Therefore, max lifting should be discouraged until after puberty.