A recent study conducted in the physical therapy department at Simmons College in Boston found more than 33 percent of children had lower-back pain that caused them to miss school, visit a doctor or abstain from activity. Also, 55 percent of children surveyed carried backpacks heavier than 10-15 percent of their body weight, which is the maximum recommended by experts.

The study also noted that early onset of lower-back pain leads to greater likelihood of recurrent or chronic problems. Backpacks that are too heavy are particularly harmful to the development of the musculoskeletal system of growing youngsters, leading to poor posture that may cause chronic problems.

The following information on backpack safely is based, in part, on guidelines from the American Physical Therapy Association. Parents and teachers would be wise to observe the warning signs of an overloaded and unsafe backpack.

Warning signs

- Change in posture when wearing the backpack. The weight of the pack forces the child to tip forward to compensate. Weak or poorly fitted straps force the child to tip to the side to compensate.

- Struggling when putting on or taking off the backpack. This can be caused by a pack that is too heavy or straps that don't fit properly.

- Pain when wearing or after wearing the backpack, caused by a pack that is too heavy or straps that don't fit properly.

- Tingling or numbness in the arms or hands.

- Red marks under the armpits or on the back.

A dozen tips

Consider the following suggestions to promote backpack safely and prevent back injury:

- Limit the weight of the pack to 10-15 percent of body weight. (So, for example, a 100-pound child should carry a backpack weighing no more than 15 pounds.)

- Make sure shoulder straps are padded and adjustable. Use both straps to distribute weight evenly. Using one strap may look cool, but it will lead to back pain.

- An adjustable waist belt will distribute pack weight from the back to the hips and legs.

- Using adjustable straps distributes weight to the small of the back and the hips, not all on the shoulders and upper back.

- A wheeled backpack may be an option for some children, but there may be problems lifting and carrying it on a bus.

- Buy an extra set of books; keep one set at home and one in your locker. Also, keep unneeded books in the locker between classes.

- Remove the backpack when possible, such as while waiting for the bus and hanging out between classes.

- Put the pack on and take it off from a chair, table or bench, not the floor.

- Stand erect and arch the small of your back - the correct posture when carrying heavy items.

- Perform posture and stretching exercises. Pinch your shoulder blades together and extend and arch your spine backward intermittently throughout the day - especially every time you take your pack off.

- Consider a backpack with multiple compartments. Use several compartments to carefully load your pack and distribute the weight more evenly.

- Use a backpack with reflective material to enhance visibility.

PAUL J. MACKAREY, P.T., D.H.Sc., O.C.S., is a doctor in health sciences specializing in orthopedic and sports physical therapy. He is in private practice and is an affiliated faculty member at the University of Scranton physical therapy department. His column appears every Monday. E-mail: drpmackarey@msn.com.

It's always a good idea to raise the level of consciousness among coaches, players and parents about the importance of injury prevention in young players. While most high school programs have certified athletic trainers on staff, I am more concerned with the youth football programs. Often these players are coached by a well-intended - but not necessarily well-informed - parent without access to trainers or other medical personnel at practices and games.

According to the Consumer Product Safety Commission, each year more than 3.5 million sports-related injuries in kids under 15 require medical treatment at a hospital or clinic. One million of those injuries are from football and basketball alone.

The American Academy of Pediatrics and the American Academy of Orthopedic Surgeons offer medical information regarding the young athlete (15 and under) and recommendations for injury prevention. High school football is different; coaches are subject to state regulation, and medical personnel and athletic trainers are present. But youth football players may be more vulnerable.

The young player

Young athletes are not small adults. Their bones, muscles, tendons and ligaments are still developing and are vulnerable to injury.

Growth plates are sections of bone that are not completely fused. These plates are very susceptible to injury, especially in contact sports. In some cases, an injury to a growth plate can be very serious.

Size variation in youth football is great. Within one age group, there can be great differences in height, weight, strength, and physical and mental maturity. Don't group players based solely on age.

Contact and overuse injuries are common in football. Contact injuries occur from an outside force such as a helmet hitting an ankle. Sprains, fractures and contusions (bumps and bruises) are examples of contact injuries. Overuse injuries occur from repetition; little league elbow and shoulder or Achilles tendinitis are good examples.

When to seek help

"RICE" - rest, ice, compression and elevation - is the best treatment for most minor injuries to provide comfort and prevent further injury until a medical professional is seen.

If the following signs are present, timely medical attention is imperative:

- Inability to play after a sudden injury.

- Compromised play because of a long-standing injury.

- Deformity in an extremity or any body part.

- Severe pain from an injury that prevents the normal use of the arm or leg.

- Cognitive change - headaches, confusion, dizziness or poor coordination - after a head injury.

- Weakness in an arm or leg with or without pain.

Injury prevention

- A physical exam is necessary before contact sports begin.

- Physical conditioning - train hard to get in good shape for your sport.

- Know the rules and techniques. Follow the rules on proper tackling, blocking, etc.

- Wear proper equipment and be sure it fits properly. Learn how to adjust straps.

- Warm up and stretch before you begin practice and games.

- Cool down after practice and games.

- Listen to your body. Take yourself out if you are too tired or in pain.

- Respect the heat - take proper precautions on hot, humid days.

- Buddy watch: Look out for your buddy for signs of problems.

- Coach watch: At the risk of being an overbearing parent, sometimes parents are right. Don't let your coach practice or play in bad weather, lightning or poor field conditions. Watch for signs that poor techniques - such as tackling with the helmet - are being taught. Coaches should encourage safe play, basic skills, proper technique, good sportsmanship and fun. Kids will have plenty of time for intense and serious play in high school and college.

PAUL J. MACKAREY, P.T., D.H.Sc., O.C.S., is a doctor in health sciences specializing in orthopedic and sports physical therapy. He is in private practice and is an affiliated faculty member at the University of Scranton physical therapy department. His column appears every Monday. E-mail: drpmackarey@msn.com.

Business travelers often find themselves with more free time in the evenings after a full day of meetings than when they are at home. While the hotel fitness room is convenient, it rarely has an attendant. What is the best method to begin a fitness program? Which exercises are best for the inconsistent novice? Are there safety guidelines?

Before you begin, discuss your intention to exercise at a hotel gym with your primary-care physician. Get medical clearance to make sure you can exercise safely.

Workout time

While a 60-minute workout would be the long-term goal, begin slowly at 20-30 minutes and add a few minutes each week. Make time to warm up and cool down. One program might include 5-10 minutes of warm-up, 10-20 minutes of strength training, 10-20 minutes of aerobics and 5-10 minutes to cool down.

Exercise routine

If you don't exercise regularly, start slowly and then increase activity level. Keep in mind:

- It's important to exercise in comfortable temperatures. In summer, if you're exercising outside, try to do it in the early morning or late evening.

- Hydration before, during and after exercise is important.

- Take a cell phone to the gym for emergencies.

Warm-up

- Spend 5-10 minutes. Good ways include walking on a treadmill or around the gym area, biking, and active and gentle stretching.

Strength training

- Begin with light weights and increase repetitions, beginning with one set of eight to 12 reps. Try it for 20 minutes, two to three times a week (don't exercise the same muscles two days in a row).

- Exercises - perform eight to 10 different exercises that train all major muscle groups: shoulders (bent-over row with weights); back (seated rows); chest (chest press with weights; push-ups); biceps (biceps curl with weights); triceps (triceps extensions with weights; push-ups); abdominals (half-crunches; core exercises on ball); gluteals (leg press; 30-degree wall slides); quadriceps (knee extensions with ankle weights; lunges; squats); hamstrings (hamstring curl); and calves (calf raises).

Aerobic

Spend 20 minutes on a treadmill or walking outside; use an elliptical, bike (recumbent bike is recommended), stepper or stair-climber.

Cool down

Spend 5-10 minutes walking, biking and stretching.

Monitoring yourself

First, determine your resting heart rate by taking your pulse using your index finger on the thumb side of your wrist for 30 seconds and multiplying it by two. Eighty beats per minute is considered a normal heart rate, but it varies. This is a good baseline to use as a goal to return to when your workout is completed.

For example, your heart rate may increase to 150 during exercise, but you want to return to your pre-exercise rate (80) within three to five minutes after you complete the workout.

For those who are healthy, calculating your target heart rate is an easy and useful tool to monitor exercise intensity. Just subtract your age from 220 to get your maximum heart rate. For example, for a 45-year-old, 220 minus 45 equals 175 - so 175 beats per minute should not be exceeded during exercise.

Some machines indicate MET - metabolic equivalent intensity for exercise - which is a measure of the energy cost of physical exercise. This is for those concerned about calories expended during exercise.

Levels range from light to very heavy. Keep the level at a light/moderate level for the first two to three weeks and advance to the moderate/heavy at week four.

The very-heavy level is for those who have a reasonable fitness level and exercise four to five days per week.

BRITTANY LUNNEY, S.P.T., a physical therapy graduate student at the University of the Sciences in Philadelphia, and DAVID FITZPATRICK, M.D., a cardiologist at Great Valley Cardiology in Scranton, contributed to this report.

PAUL J. MACKAREY, P.T., D.H.Sc., O.C.S., is a doctor in health sciences specializing in orthopedic and sports physical therapy. He is in private practice and is an affiliated faculty member at the University of Scranton physical therapy department. His column appears every Monday. E-mail: drpmackarey@msn.com.

Aug. 16 is the first day of full-uniform and full-contact football practice for Pennsylvania high schools - prime time for heat-related illness.

Heatstroke is the result of long-term sun exposure to the point of being unable to sweat enough to lower body temperature. The elderly and infants are most susceptible. It can be fatal if not managed properly and immediately.

The exact cause of heatstroke is unclear - one reason prevention is the best treatment. It can also occur in nonathletes at outdoor concerts, outdoor carnivals or backyard activities.

The American Academy of Pediatrics and the American College of Sports Medicine offer these suggestions:

Signs of heatstroke

- Heat exhaustion - can be a precursor to heat stroke. Signs are cramps, weakness, fatigue and nausea. Treatment: rest in shade, cool down with cool (not cold) towels and drink plenty of fluids.

- Core body temperature above 105 degrees.

- Hot, dry skin - flushed but not sweaty.

- Lack of sweating. But note that athletes often have external heatstroke and can sweat even with an increased core temperature.

- Very rapid pulse.

- Mental confusion, disorientation or hallucinations.

- Physical clumsiness, sluggishness or fatigue.

- Seizure.

- Dizziness.

Heatstroke treatment

- Call 911. Remember, this may be life-threatening.

- Relocate. Get to a cool, shady place or air-conditioned indoor room and lie down, with slight elevation of the feet.

- Undress. Remove outer garments and roll onto side to expose as much skin as possible to the air.

- Cool down. Spray or sponge with cool water (not cold) and a fan.

- Ice. Place ice packs to the groin, neck and armpits to cool down large blood vessels, but don't take an ice bath.

- Check core temperature. This is the only accurate measurement, so medical personnel may take a rectal temperature. The core temp must be reduced to 102 as soon as possible.

- Begin CPR if breathing stops.

- Do not use aspirin or acetaminophen.

- Administer fluids. If the victim is alert enough to swallow, give 32 to 64 ounces over one to two hours.

Heatstroke prevention

- Gradual acclimatization to heat. Get used to the heat gradually. Begin short conditioning sessions in early summer. Have shorter and less intense practices for the first seven to 10 days. If you've recently had the flu or an illness with a fever, stay home for a while and gradually introduce the heat and humidity with short periods of exercise.

- Humidity index. Be very aware of the temperature and the relative humidity. The humidity index equals temperature plus humidity. If the sum is 160 or more, take serious precautions (short sessions in early morning or evening, shorts and half-pads, plenty of water and sports drinks). If the sum is 180 or more, practice and games should be canceled.

- Take frequent breaks. These should be 15 minutes after each hour if the humidity index is 160 or above. Rest in shaded areas, helmets off, and jerseys loosened or off.

- Unlimited cold water. This should be available at all times. Water breaks should be mandatory every 15-20 minutes. Break in a shaded area and water down your head and neck. Avoid caffeine drinks, carbonated drinks and alcohol.

- Electrolyte sports drinks are helpful to replace electrolyte loss. Do not use salt tablets.

- Dress for heat. Use material under pads that will wick sweat away from the body, and change shirts at break. Wear light colors. Use fishnet jerseys over your pads to keep cool. Remove helmets often in hot weather.

- Medical files. Coaches should keep an index of individual athletes with medical problems or a history of problems, especially those at risk for heat-related illness. Certain medications may put an athlete at risk for heat stroke. Pay special attention to those players.

- Keep alert. Coaches, parents and players must be on the lookout for signs of a problem in themselves and their teammates. Don't ignore signs of distress. If you see signs of a player in distress or signs of poor practice management that may jeopardize the health of an athlete, diplomatically speak up. Use references to educate those in charge to recognize their mistakes and improve conditions. Usually, problems occur not because of malice but because of ignorance.

PAUL J. MACKAREY, P.T., D.H.Sc., O.C.S., is a doctor in health sciences specializing in orthopedic and sports physical therapy. He is in private practice and is an affiliated faculty member at the University of Scranton physical therapy department. His column appears every Monday. E-mail: drpmackarey@msn.com.