What To Do When You’re Injured: Introducing You To CaptainU

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

Clinical Assistant Professor of Orthopaedic Surgery, Stanford University

This month we’ll be starting collaboration with a great company called CaptainU. We’ll feature CaptainU podcasts periodically, on fitness and performance issues of importance to young athletes. I think you’ll find these podcasts relevant, interesting, and occasionally controversial- which makes for great listening!CaptainULogo

First, a few words about CaptainU.  This is a great service principally targeted at connecting young athletes seeking to play their sport in college, their parents, and college coaches.  Together CaptainU has built a substantial community of about 500,000 members. By way of a disclaimer neither Sideline Sports Doc nor I have any financial relationship with CaptainU but our family believed strongly in what the CaptainU service can do so we paid for CaptainU subscriptions for our sons when they were going through their college selection process.  We found the service extremely helpful for researching and communicating effectively with coaches, and their advice for the process of college recruiting was absolutely correct.  As a young athlete if you market yourself correctly to the best-fit colleges your chances of gaining a spot on a college team are actually quite good. Not only is their method effective but it’s actually fun! Their “Make The Team” eBook is available for free download from our website.

Several months back, CaptainU started a blog and series of podcasts delivering information on a variety of sports related topics relevant to high school aged athletes. I’ve had an opportunity to be on their show a couple of times now and as we get our work with CaptainU kick-started I’d like to feature a podcast I did with them titled: “What To Do When You’re Injured”.  You can access it here:

The podcast lasts about 30 minutes- perfect length for a drive to and from practice, or plugging in during a training run.  Here are some of the key points that we cover in detail:

  • Prevention starts with appropriate preseason conditioning
  • End of season injuries are common simply because the athlete has been exposed to more training and games, which makes a body vulnerable to injury
  • In-season injuries that are evaluated and treated properly by a trainer, physical therapist, or sports medicine physician can often be effectively treated at the same time the athlete can remain playing.
  • If you just can’t perform in the way you must to be effective in your sport because of a lingering injury you need to seek some help.
  • “Pain” is not normal for a young athlete. Almost all young athletes are capable of making a difference between “pain” and “soreness”. If you think you have pain, get help and get on the path to healing.
  • Communication with the coach also needs to start in the preseason, noting that the health of the athlete is critical to the team’s overall success.
  • An athlete should use the athletic trainer for school sports and their parents for club sports as an intermediary when it’s necessary to discuss an injury.  A clear line of communication with the coach is important, and timing of the discussion is important too (never right after a game!).
  • If you do have to take time off from your sport to rehab an injury you can almost always come back stronger and better than you were before.
Posted in CaptainU, Tips and Training | Leave a comment

Tiger’s Back: Could It Happen To A Young Athlete?

tiger's backBy Dev K. Mishra, M.D.

President, Sideline Sports Doc

Clinical Assistant Professor of Orthopaedic Surgery, Stanford University

The Master’s Golf Tournament has a bit of a hollow feeling this year.  As I write this post it’s Saturday morning and the third round has yet to get underway, with no Tiger, no Phil, no Dustin…and about 20 other “big name” golfers also out of the picture.  For several of those golfers a balky back has led to decreases in performance, and in Tiger’s case it’s required surgery. For the young athletes we focus on, when is back pain something to really pay attention to, and could a serious injury requiring surgery happen in a young athlete?

Is it a “sore back” or is it “back pain”?

Many young athletes will have an occasional sore back as part of the normal process with a sport.  This is especially common in sports requiring twisting or torsion on the back such as gymnastics, golf, tennis, and lacrosse. In general, a sore back will involve mild to moderate discomfort and will tend to be located along the large strap muscles in the low or midback.  Soreness will generally resolve with simple treatment such as ice/heat, rest for a few days, and perhaps some anti-inflammatory medication such as Advil.

Red Flags that signal a possible serious injury

There are a few things to be on the lookout for that could signal that the problem is something more significant than simple muscle soreness.  Watch for these things and seek evaluation and treatment from a sports medicine physician soon:

  • Did the pain start with an injury associated with a “pop” or sudden sharp pain?  This could be a sign of a stress fracture, or rarely a disc injury.
  • Is it “pain” or “soreness”?  This is a tough call, as each of us will have a slightly different personal definition of “pain”.  But in my experience a young athlete definitely knows when something is “painful” vs. “sore”.  If the complaint is about “pain”, seek evaluation urgently.
  • Any numbness or tingling going down the legs or buttock?  This could be an injury to a disc or to the bone causing nerve irritation.  Proper early evaluation and treatment is important.
  • And if it’s soreness that’s lasted more than about 2 weeks, you’d be wise to seek proper evaluation.  In my medical practice this is a common reason for young athletes to seek care.  Back soreness that lasts more than about 2 weeks is uncommon and often means there’s an underlying cause.  I have seen a big jump in the number of young athletes with this scenario, and oftentimes we find that they have a condition called a “stress reaction” or even a “stress fracture” in one of the lower back vertebrae.  This condition can lead to a lifetime of low back problems if not treated, but can usually be fully rehabilitated without long-term consequences if treated properly.

With some sports it’s impossible to completely eliminate the stresses placed on the spine. If you have any of the “red flag” conditions I’ve outlined above then you should get some help from a sports medicine physician.  Any golfer would love to play like Tiger or Phil at their prime, but I don’t think any of us want their backs.





Posted in Back, In the News, Sideline Sports Doc Miscellaneous | Leave a comment

Youth Sports Can Be Great, Lifetime Fitness Is Better

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

Clinical Assistant Professor of Orthopaedic Surgery, Stanford University

We spend quite a bit of time and focus in Sideline Sports Doc on competitive sports. Today’s post is on a related but slightly different subject- the benefits of continued fitness after the athlete’s competitive playing days are over. swiss ball core

Health and fitness experts have spoken of the benefits of lifetime fitness for years but interestingly the solid evidence of the benefits of exercise leading to improved health, quality of life, and living longer were lacking. But recently published data points us convincingly in this direction: lifetime exercise can help you live longer.

This excellent study can be accessed in its entirety here, published in the journal PLOS One in December, 2013.  The researchers from Curtin University in Australia conducted an ambitious study to prospectively evaluate more than 8000 people over a 15-year period. The purpose was to evaluate the effects of exercise on cardiovascular health and lifespan.

The study results showed that exercise in and of itself is an important positive factor in promoting overall health.  This was true even if the individuals were obese, and it was true even for light forms of exercise such as walking.

Why would this be important for the young athlete?  Simply because I see too many athletes start to ignore basic fitness once their playing days are over.  How many times have you seen a “where are they now” television show that reveals the former elite or professional athlete is obese and out of shape? In my medical practice I’ve seen this happen as early as middle school.  A league is competitive, the youngster is unable to make a particular elite team at around age 13 or 14 and instead of channeling their interest to other physical activity they decide to quit all physical activity.

To encourage continued participation in fitness activities beyond formal playing days there are a number of steps we can take.

  • For the youngest kids, parents and other adults will serve as role models. Demonstrate to them that you feel fitness is important by engaging in regular exercise yourself.  This is a very powerful motivator.
  • In middle school, we need to make sure there are outlets for athletes who are unable to participate in their elite level team of choice.  Maybe it’s time to try another sport, even a school sport where competition is present but the pressure may be less? Maybe a rec league in the same club sport?  Many options exist, as parents we need to explore these when appropriate.
  • Some athletes, especially in college, can have a playing career cut short by injury. This can be psychologically devastating, and here as well it’s important for family members or other role models to demonstrate that life will go on and fitness needs to remain a part.

The evidence is definitely in.  Keep yourself moving. Keep yourself active. Live longer.

Posted in In the News, Performance, Sports Science | Leave a comment

Resistance Training: Beginners Should Start Slow And Advance 10%

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

Clinical Assistant Professor of Orthopaedic Surgery, Stanford University

This week we’ll take one final look at a section from the consensus statement in the British Journal of Sports Medicine regarding the benefits of resistance training for young athletes. How should a novice young athlete start and how rapidly should they advance? strength

The section titled “Progression of Volume and Intensity” stated again that the authors prefer that all young lifters participate in programs supervised by qualified youth strength and conditioning specialists. The key take-aways were:

  • Focus for the true beginner must be on safety and proper technique
  • Novices should start with low volume (1-2 sets) and low lifting loads
  • Increase loads over time as long as proper form is maintained
  • Multijoint training (such as squats) require particular supervision and a very small number of reps to start (1-3 reps for novices)
  • The young athlete can progress to higher loads 6-8 reps per set over time, with perfect form maintained

My Take: Start Low and Slow

Last week I mentioned that in general I really like starting the young lifter with body weight exercises and resistance bands, and then progressing to free weights and machines. My perspective as an orthopedic surgeon may be different than that from a strength specialist because kids only come to the orthopedic surgeon when there’s been an injury.  So our bias is that we see what’s gone wrong.

The most common problem that brings kids in to our office is starting (and continuing) with loads that are too high.  This places excessive strain on young tendons, and especially tendon insertions into bone.  Around the knee a condition called Osgood-Schlatter syndrome and in the foot Sever’s syndrome are painful conditions resulting from overloading.  So tip #1 from the orthopedic surgeon: start with very low loads, aim for perfect form, and back off if you have joint pain. “Stay slow” means you perform the movements slowly with perfect form.

Use the “10% Rule” to Guide Advances

The following point was not mentioned in the consensus statement but many knowledgeable youth sports trainers recommend the “10% rule” in guiding advances in loads.  Simply stated, you can increase the load by 10% each week, as long as your form remains perfect and you have no joint pain.  If for example you’re using 5 pounds for a particular exercise and you’d like to increase the weight for next time you would add 10%, which is a half pound, and aim for 5 ½ pounds next time.  Many times that won’t be possible, as there are no 5 ½ pound weights, so you’d get as close as you can to that.  The point is that you don’t go from 5 pounds to 10 pounds; pick the closest increase to 10% instead.

So start low, stay slow, and use the 10% rule to guide your increases in load to give you the best chance of getting stronger safely.

Posted in Performance, Science, Tips and Training, Training | Leave a comment

Resistance Training Start-Up Basics For Young Athletes

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

Clinical Assistant Professor of Orthopaedic Surgery, Stanford University

Last week I wrote about the recently published consensus statement in the British Journal of Sports Medicine regarding the benefits of resistance training for young athletes. This week I will take a look at one section regarding the best way to start, and types of exercise.  Next week we’ll conclude with a review of the section on how rapidly to advance training. group strength training

The section titled “Exercise Selection” began by stating that all kids will be at different levels of technical ability and baseline levels of fitness when they start. Furthermore, there may or may not be access to a skilled instructor or child-specific equipment. With that in mind there are some key take-aways:

  • Focus for the true beginner must be on safety and proper technique
  • Body weight exercises and resistance bands are the safest and easiest methods for the beginner
  • Machines also offer a level of safety and can be used by beginners with proper supervision
  • Free weights have been shown to be more effective at building strength than machines, free weights should be used when a foundation of technical skill and baseline strength have been achieved
  • Advance the young athlete to plyometric activity (with bounding, jumping) last

My Take: Inexperienced Athletes Should Begin With Bodyweight and Bands

I completely agree that the safest way for the true beginning athlete with little to no experience in resistance training should be to start with bodyweight or resistance band training.  In fact, bodyweight exercises are incredibly effective and can be modified in many ways to increase loads.  You would be surprised how the variations can change loads by changing body position.  There are many excellent sites on the web and several excellent apps that provide video instruction in proper form.  The bands are available at almost all sporting goods stores and will come with printed or DVD instructions in proper usage.  I highly recommend these as safe, easy, low cost, and portable. In my opinion a bodyweight and band program does not require supervision by a trainer.

Beyond Bodyweight and Bands: Get Some Help Before Starting Free Weights

When you start putting free weights in the hands of young athletes you are introducing potential safety hazards.  In this setting I agree with the authors of the consensus statement, this athlete should receive proper supervision.  At least for the first several sessions I think it would be wise to work with a personal trainer at a gym who has skill and experience with the athlete’s age group, or to seek out small group training programs.

Beyond Free Weights: You Must Absolutely Get Supervision For Plyometric Training

Plyometric activities involve explosive movements such as bounding or jumping. I see a lot of injuries from plyometric training in kids and adults.  If done right, plyometric training will probably make you faster and quicker.  But if done wrong they are huge injury generators.  Definitely work with a skilled trainer when you start a plyometric program.


Posted in Performance, Science, Tips and Training, Training | Leave a comment

Giving The Green Light To Resistance Training In Young Athletes

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

Clinical Assistant Professor of Orthopaedic Surgery, Stanford University

I am frequently asked questions about resistance training (otherwise called “weight training”) for young athletes.  Is it “right” or “wrong”?  When is the right age to start?  How can it be done safely?  A recently published consensus statement in the British Journal of Sports Medicine from several highly renowned sports medicine professionals has detailed answers.  Short answer: properly performed resistance training can be done safely and effectively by young athletes.  Girls can do anything!

Let me start by summarizing and paraphrasing some of the key findings in the paper, which are presented in bullet form at the paper’s conclusion (I will offer commentary after the summary):

  • Resistance training programs in children and adolescents can be done safely and effectively as long as the programs are designed and supervised by qualified professionals
  • There are long-term health benefits from participation in resistance training, and negative health effects for kids who do not participate in regular fitness activity
  • Resistance training is an important component in injury prevention
  • Early participation in resistance training and physical activity can lead to lifelong fitness activity
  • Resistance training should be customized to age, motor skills, technical proficiency, and baseline strength
  • Focus on the earliest stages of resistance training should be on proper form and technical skill

And now for some of my commentary.  Overall I think this is an excellent reference paper that goes in to great detail.  Many of the points above are things that sports medicine professionals have believed for a long time but what we were lacking was evidence based proof in the medical literature.  This summary paper attempts to outline the proof.  I commend the authors for assembling a world-class group of professionals and garnering the backing of a number of prestigious health organizations to support the findings.

But I am somewhat concerned that the paper recommends that the programs be designed and supervised by qualified professionals.  My concern is twofold: access to these qualified professionals, and cost to the family.  I think about the area where I live- the San Francisco Bay Area- and I know there are just not enough qualified professionals here (as defined by the paper) to work with the kids.  I suspect this would be true in most parts of the country.  The second issue is cost.  If these programs exist it’s possible that the cost would be prohibitive for many families.  Physical Education programs at schools are trying to do a good job but their budgets are constrained too.  We need to find a way to allow safe participation for the broadest segment of kids.

The paper is not easily accessed unless you are a medical professional, so over the coming weeks I’ll dive a bit further into some aspects of the paper with summary and commentary.

Posted in Performance, Science, Sports Science, Tips and Training, Training | Leave a comment

Keeping Your Core Healthy

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

Clinical Assistant Professor of Orthopaedic Surgery, Stanford University

In recent posts we’ve been discussing the importance of the large lower extremity muscles and core, especially for sports such as baseball.  Today we’ll take a brief look at a few maintenance tips for the two dominant muscle stabilizing groups, the latissimus dorsi and gluteals.  latissimus-dorsi

The latissimus dorsi is a large muscle extending from the upper arm, to lower back and pelvis.  It links a number of bones and joints critical to any throwing or rotational movement.  The gluteals are large muscles covering your pelvis and upper leg (the butt muscles).  There is a sheet of tissue covering the muscles and under the skin called “fascia” that functions as a link between the muscles.  Taken together the lats and glutes from the left and right sides of the body form an “X” in your back and pelvis.

Over the last few years we’ve learned much more about the importance of the fascia. The fascia is not just a dormant wrap covering the muscles, but has cells sensitive to pressure that allow communication throughout the entire body. The fascia covering the lats and glutes is particularly important in transferring force between the spine, pelvis, and lower body. The healthier this tissue is, the faster and more effectively forces are transmitted when you run, throw, or jump.

Strengthening The Lats And Glutes

There are several large muscle group functional strengthening exercises that are very effective in targeting the lats and glutes. These exercises use multiple joints and multiple muscle groups and are excellent for almost all young athletes.  For the youngest age groups they can be done with body weight alone.  For proper guidance consult a qualified sports trainer or physical therapist.

  • Pull ups (overhand grip)
  • Rows (upright and bent)
  • Squats

Improving The Health Of The Fascia

For the fascia to function properly it needs to have resiliency or flexibility, and it needs to glide smoothly.  The biggest fascia problem that I see in young athletes is scarring, which then results in limited gliding of the fascia.  In the athlete this can be experienced as stiffness or pain.  “Muscular” low back pain often has a component of fascia adhesions, and these must be corrected to restore proper function.

There are two maintenance exercises that can be very effective in preventing adhesions in the fascia.  They are:

  • Proper dynamic flexibility exercise.  The folks at EXOS (formerly called Core Performance) have a great set of videos demonstrating five basic core flexibility exercises.  Access it here and do these daily.
  • Foam roller for self massage.

If you are having pain…

If you are experiencing pain you should consult a sports medicine specialist for proper diagnosis and a treatment plan.  There are several excellent techniques used by physical therapists and athletic trainers such as Active Release Technique and the Graston technique that can restore pain free function to athletes with muscle or fascia problems.





Posted in Back, Hip, Prevention, Science, Therapy, Tips and Training | Leave a comment

How Long Should A Young Athlete Rest?

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

Assistant Clinical Professor of Orthopaedic Surgery, Stanford University

In January I wrote a post titled “3 Things High School Athletes Must Do Between Seasons”.  The summary of the three things is 1. Get some rest, 2. See a sports medicine specialist if you have nagging injuries, and 3. Start a proper preseason conditioning program prior to your next sport season.  I received a lot of comments centered on point #1, specifically, how much should a young athlete rest?Image

First let’s make some assumptions, specifically that you didn’t finish the prior season with anything that you would describe as ongoing pain, and that you didn’t have a nagging injury that negatively effected your performance.  In other words, let’s assume you finished your prior season tired, maybe sore, but otherwise intact. The exact amount of time for “rest” will be different for each individual, and will differ in the youngest age groups, sport, and level of play.  But there are some general guidelines applicable to all groups.

One of the main considerations is that the time between seasons has become very short for many athletes. For older competitive athletes (teenagers, late adolescence) one poor offseason could negatively affect the upcoming season. The offseason- however brief it may be- is very important.

Total rest from all physical activity can be unhealthy

Total rest has a balance point, as too much time completely off from all physical exercise has negative effects. Some studies have shown that 4 weeks of total rest can cause a 15% decline in power. For example, athletes could experience a 3.5 to 5 inch drop in vertical jump!

Furthermore, total inactivity has a negative effect on the strength and quality of connective tissue in the body. A “tendon” is a structure that connects a muscle to a bone; common examples are the Achilles tendon at the ankle and the patellar tendon at the knee. Prolonged periods of inactivity, also called “detraining” have been shown in animal models to decrease the quality of tendon tissue.  It’s difficult to know how well these findings would translate over to human beings but it’s reasonable to say that complete inactivity has the potential to negatively affect the structure of key soft tissue components in the young athlete’s body.

A much better option is “relative rest”

Putting all of these points together, I typically advise the athlete to perform what we call “relative rest”, meaning that you may take time off from the rigors of your sport to recharge mentally, and during that time perform safe activity that allows physical regeneration too.  For example, athletes involved in jumping and sprinting sports such as basketball or soccer would continue with low impact activity such as bicycling, elliptical trainer, and upper extremity weight training.  I’ve generally seen that 2-4 weeks is needed for the athlete to feel mentally and emotionally fresh and ready for the next sport season, while balancing the needs for some physical maintenance.

So here are a few tips on rest, whether it is the start of your offseason or not.

1. Rest between sports and seasons is a good time to mentally recharge and restore motivation

2. Apply the principle of “relative rest” during your time off; stopping physical activity entirely could have negative consequences

3. The amount of time for relative rest varies tremendously for each individual, but I’ve generally seen 2-4 weeks as adequate time to recharge for the otherwise healthy teenage athlete.  See your sports medicine professional for specific recommendations.


Posted in Prevention, Psychology, Science, Sports Science, Treatment | Leave a comment

Throwing From The Ground Up

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

To most observers baseball pitching looks like it’s an upper body activity. However, researchers have found that like many rotational movements such as golf swings and tennis serves, it involves the lower body and trunk musculature extensively. In fact, our most current knowledge of the motions required in throwing suggests that the action whip1starts from the ground and works its way up.  Somewhat like a whip, movement in the handle of the whip (the legs) results in a rapid movement and “snap” at the tip (the hands).

Much of the credit for our knowledge about the throwing motion goes to pioneer orthopedic surgeon researchers such as Dr. Frank Jobe in Los Angeles, Dr. James Andrews in Birmingham, AL, and Dr. Ben Kibler in Lexington, KY.  When a proper throwing motion starts, the pelvis is rotated using the leg and hip muscles. The pelvis accelerates but then quickly decelerates as it transfers energy to the torso. The same pattern is repeated with the torso and the arm and then the arm and the hand, club, bat or racket.  When the sequence malfunctions (through weakness, lack of coordination, imbalance, etc.) the throwing motion can break down, leading to injury.

Here are some key points we can take from the research to date:

  • The ground-to-hand energy transfer seems to occur during baseball pitching, with the movement being initiated by the legs, transferred through the pelvis to the torso, through the arm and finally into the hand.
  • Leg drive is important for pitching velocity. Improving the strength and power of the legs should improve pitching performance.
  • Since starting pitchers may have to perform approximately 60+ pitches per game, muscular endurance training for the legs is important.
  • While all leg muscles are very involved in the pitching action, the activity of the gluteals is strongly correlated with proper pelvis rotation, suggesting that specific gluteal training may be worthwhile.
  • The adductors (groin muscles) may be more involved in the pitching movement than we originally believed, suggesting that specific adductor exercises should also be a part of lower body conditioning for throwing.

So, leg strength and power are important to baseball pitching and other throwing sports.  The concept of the “whip” sequencing is likely one of several important factors involved with successful throwing. Obviously, proper mechanics are critically important too. So, while leg strength and power are important to baseball pitching, we can’t forget about correctly training this sequence.  This is why proper coaching at a young age and proper strength and conditioning programs that understand this concept are necessary.


Posted in Baseball, Elbow, Performance, Prevention, Shoulder, Tennis, Tips and Training, Training | Leave a comment

You Need To Train Like An Olympic Athlete

By Dev K. Mishra, M.D.

President, Sideline Sports Doc

I’m sure you’re watching at least a little bit of the Winter Olympics, and hopefully you’ve been impressed with some of the spectacular performances.  What’s interesting to me is that the outdoor events are in almost “tropical” conditions, at least as far as events conducted on snow are concerned! The athletes have devoted several years leading to this two-week competition and in many cases they’ve devoted their lives to get them to this point. Is there anything the young athlete can learn from Olympians’ training methods?DynamicStretch

Elite Olympians Are Preparing For Competition Year-Round- Which Includes Time To Rest In The “Off-Season”

Olympic athletes are training all the time, but they train with the total package of rest, regeneration, nutrition, psychology, etc. They are training in season and the off-season. A concern I have for young athletes in competitive sports is that for many of them there is absolutely no off-season.  Club season is followed by high school, followed again by club. I ask young athletes about their time off and I commonly hear things like “yes, I took a couple of weeks off at Christmas.” The Olympic athlete focuses on strength, flexibility, balance, and technical execution. The young athlete would probably have better performance and fewer injuries if they followed the example of the Olympian.

You must have some time off to rest and regenerate

The young athlete who is really interested in top-tier performance needs to have time off to train like an Olympian. Think about doing routine flexibility and strengthening exercises and keeping your body balanced, because that reduces injury. Proper biomechanics and muscular balancing is conclusively proven to reduce injury.

Focus on proper preparation for your upcoming sport during the preseason

There’s no doubt that Olympic athletes have resources that most young athletes don’t have access to, such as round-the-clock expert trainers and other consultants. Still, there are areas that the young athlete can focus on that will pay great dividends once the regular season comes around.  For example throwers should concentrate on strengthening the scapular stabilizers, the core, and the legs.  This can be done now during the cold end of winter months in preparation for upcoming spring baseball.

Perform maintenance exercises for key muscle groups while you are in season

In next week’s post we will take a closer look at the importance of the legs and core for throwing sport athletes such as baseball players.  Regardless of your sport, you would be well served if you could take some time during each week to do maintenance exercises for the key muscle stabilizers for your sport.



Posted in Hydration, Nutrition, Performance, Prevention, Psychology, Tips and Training | Leave a comment