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Exercise-Induced Microscopic Hematuria Developed 12 Hours After Powerlifting

C. Thorsten
March 2007

Abstract:  Athletic pseudonephritis was studied in an apparently-healthy test subject after a workout with maximal to maximum poundages in the squat, bench press, and deadlift exercises.  Urine sediments exhibited microscopic changes that became evident approximately 12 hours post-workout.  The presence of hemoglobin and / or degraded erythrocyte residues was noted only in the specimens collected c. 12 hours after exercise.  Compaction of these residues into casts seemed dependent on whether the subject had slept or stayed active before specimen collection.

Introduction:  Much of the past work on sports-induced hematuria has revolved around marathon runners and boxers (see for example Siegel et al., 1979), with apparently little attention to weightlifting and powerlifting.  The latter is an extremely strenuous anaerobic activity carried on using nearly the heaviest weights that the athlete is capable of moving.  Powerlifting introduces enormous short-term physical strains and muscular demands;  advanced strength athletes routinely handle weights well in excess of bodyweight.  Heavy squats and deadlifts in particular have a reputation among lifters for increasing testosterone secretion;  this in itself presents an interesting area of study with regard to biochemical and physiological changes in various organs, including the kidneys.
It is by now well-known that exercise can induce temporary, generally harmless nephrologic changes that mimic serious kidney disease.  While actual renal failure is possible during or after most any sort of strenuous exercise, it normally requires aggravating factors such as dehydration or chronic use of non-steroidal anti-inflammatory drugs (NSAIDS). 
The present case study employed test subject who was apparently healthy in all major respects and engaged in minimal to zero use of NSAIDS and antibiotics.  There was no hypertension, diabetes, or other notable condition;  there was no smoking and no use of any other medication or drug.  Abundant hydration was ensured during all exercise sessions.
Materials used:
Droppers & Pasteur pipettes
Urine Reagent Strips (9-parameter)
Compound Microscope (Observer III)
Slides, glass
Coverslips, glass
Centrifuge, Ultra 8V
Mini-VID eyepiece camera

Methods & Observations:

The microscope was an Observer III, having a maximum of 400x magnification.  The eyepiece camera was a Mini-VID USB. 
Test subject was a male volunteer, age 30-35.  Body weight was 200 lbs (91 kg).  There was no evidence of underlying renal pathology or other afflictions.
The volunteer reported eating mostly balanced meals, with general avoidance of alcoholic beverages, carbonated soft drinks, and deep-fried foods.   Regular diet included a multi-vitamin supplement taken once per day.
Other dietary factors noted were (1.) regular post-workout consumption of extra protein, and (2.) overall caloric intake of ca. 3000 calories per day, including anywhere from 90-150 grams daily protein in total.  Neither of these habits was deemed at all unusual for a weightlifter.
In order to limit variability, the only solid meals consumed on the day of each test trial consisted of rice and lentils;  all other food intake consisted of a protein drink containing 25 g. of pure whey protein ( Inc., PO Box 626, Middlesex, NJ) in 8 oz. of water.   The whey protein was chosen for its lack of additives of any kind (e.g.,  added glutamate, artificial sweeteners, etc).
Two trials were conducted over the course of two weeks;  see "experimental schedule", below.

Exercise routine:
Weight-lifting for the experiment consisted of approximately 45 minutes of heavy, low-repetition barbell squats, deadlifts and bench presses.  Poundages were such that only 1 to 3 repetitions were possible per set.  Two sets of this type were done for each exercise, with the 2-3 warm-up sets in each case having been done at ca. 70% or less of maximum poundage.  In keeping with the test subject's typical weightlifting pattern, at least one sub-maximal, low- to mid-repetition set was also done after the maximal / maximum ones.  In both trials the subject did the workout  in the evening, as was his normal habit;  exercise commenced at about 8:30 PM.
Subject was allowed to consume 30 g of whey protein (suspended in pasteurized, low-fat milk) and one tablet of a C & B-vitamin supplement, as was his normal post-workout habit. 
A second whey protein "shake" was consumed 2 to 2.5 hours after the workout, which was also the lifter's normal, post-exercise habit.

Experimental schedule:
In this test athlete the microscopic hematuria was delayed in its onset and could be narrowed exclusively to the specimen obtained 12 hours post-workout (margin of +/- 30 minutes).  However, all instances of renal clearance were collected and examined as they became available.  Samples collected before or after the 12-hour specimen showed virtually no microscopic hematuria or other formed elements;  although all samples were kept, they had little of interest relative to the 12-hour sample.  
It is important to reiterate here that even samples collected as little as one hour before or after the 12-hour specimen showed virtually no elements of interest.
The experiment was done twice over the course of two weeks:

Trial 1:  The subject went to sleep about 3 hours after the workout.  A first-morning specimen was collected 12 hours post-workout (the "resting" 12-hour sample).  Samples from before going to sleep were kept and refrigerated at 4-8ºC.  Subject was to collect any samples voided prior to collection of the 12-hour sample;  there was one such sample, kept at 4-8 ºC until it could be examined

Trial 2:  The subject stayed awake all night and went through a normal waking routine (walking, sitting, standing- but no strenuous exercise) for the whole time after the workout.  A specimen was collected 11 hours 45 minutes post-workout (the "waking" 12-hour sample).  Several other specimens were collected before and after this time.

Sample collection & preparation:
A freshly-voided sample was collected in a centrifuge tube and promptly studied, with a new one collected at each timed interval.  Visual examination and reagent strip assays were performed before centrifugation.
Samples were centrifuged at ca. 2500 rpm for 10 minutes in the Ultra 8V.  In each case the supernatant liquid was pipetted mostly away, leaving 0.5 mL of liquid in which the sediments were resuspended.
Timing of sample collection was based on actual renal clearance rather than a uniform interval.

Visual examination:
In both trials, only the "12-hour" specimen showed any noteworthy characteristics.  These specimens became extremely cloudy when chilled;  centrifugation in both cases yielded an opaque pellet with macroscopically evident blood.  It is important to note that blood was not visually evident before centrifugation (i.e., no gross hematuria).
These properties were consistent with a test run that was conducted several weeks prior on the same subject.

Multi-reagent strip tests:
All tests appeared normal / negative, with only "slight trace" or no protein being detectable at any time, despite the fact that the "12-hour" samples became extremely cloudy when chilled.  pH was consistently in the 6.0-7.0 range throughout the tests.  Specific gravity was 1.020-1.030.
Though there were visual traces of blood and/or hemoglobin pigment in the sediments of both 12-hour samples, the samples hadn't shown any such visible traces before centrifuging.  They evidently didn't present enough blood for the reagent strips to detect. 

Sediment Microscopy:
No stain was used in most cases, since most of the formed elements of interest were visible without any added colorant.
Specimens collected before and after the 12-hour samples were inspected just to be certain they contained no casts or other important formed elements;  this was verified and the specimens put aside.
In all cases, the usual calcium oxalate (weddelite) crystals formed upon standing, especially at lower temperatures as would be expected.  There was also some uric acid, amorphous phosphate, and other, typical crystals.

Figure 1.  Typical microscopic appearance of all centrifuged samples (except for the 12-hour);  in other words, there were virtually  no formed elements of interest.

Magnification: 100x.
Click for larger image

Figure 2.  Casts of any kind were extremely scarce in most centrifuged samples (except the 12-hour).  Shown here:  an isolated hyaline cast from a 3.5-hour post-workout centrifuged sample.  This was the only cast or cast-like element noted in any of the non-12-hour  samples.  

Magnification 100 x.
Click for larger image

Figure 3.  The "resting" 12-hour sample, obtained from Trial 1 of the experiment.  Note the dense, brownish cast composed of hemoglobin / degraded RBCs.  There were many such casts in the sample.

Figure 3a:  Another view of the 12-hour sample from Trial 1.  Some of these casts served as nucleation points for calcium oxalate crystals that later formed in vitro.   The RBC casts, not the crystals, were the important elements.

Magnification: 100 x.
Click for larger image

Figure 4.  The "waking" 12-hour sample, obtained in Trial 2 of the experiment.  Casts, when evident, were very diffuse ("pre-casts"), but there was significant hemoglobin / degraded RBC debris.

Magnification 100 x.

Click for larger image


A relatively short period of powerlifting-- a maximally-strenuous, anaerobic exercise-- caused significant but temporary nephrologic changes in a healthy test subject.  These transient changes appeared almost exclusively in those specimens collected approximately 12 hours post-workout.  Their predominant microscopic feature was abundant hemoglobin residue and/or heavily-degraded erythrocytes.
All other specimens pre- and post-workout were studied carefully under the microscope but showed virtually no transformation, with the possible exception of increased crystal formation.  One sample contained crystalloid masses of what appeared to be ammonium biurate, but their identity was not confirmed.  There was not enough crystal formation to deem noteworthy, however.
The 12-hour samples indicated a fairly sudden but temporary leakage of blood into the renal filtrates.  It is commonly-known that strenuous exercise can increase glomerular permeability, allowing macromolecules and erythrocytes to pass into renal filtrates.  In the present experiment, the concentration of hemoglobin and/or degraded erythrocytes in the 12-hour samples suggested a definite but delayed increase in glomerular permeability.
Although the turbidity observed in the chilled 12-hour samples was most likely protein, the urine reagent strips did not detect it.  While it may be that the proteins released during the experiment were not the ones for which the test was designed, it seems even more likely that there was interference.  The test strips will detect albumins but not globulins, even though both were probably present in the sample.  It is important to realize here that, if the relatively gigantic red blood cells were able to pass the glomeruli en masse, the globulins would easily have passed as well.  We might even expect the contents of the urine here to have reflected the relative composition of blood plasma proteins;  this composition, in turn, may have been special for a subject who powerlifted and consumed large amounts of dietary protein.  In any case, a more generalized lab method for protein could have yielded better results here.  The use to which the strips were put in this experiment was not quite the intended one;  however, it did give some rough figures to suggest there were no glaring abnormalities (e.g., glucosuria, aciduria / alkalinuria) in the test subject.
In the weightlifting world, heavy squats and deadlifts are virtually synonymous with testosterone and a resultant increase in body muscle mass.  One may recall the story of Peary Rader, who transformed himself from the proverbial "100-pound weakling" (in his case, 128 lbs) into a 210-lb athlete possessing fearsome strength (Strossen, 1992).  While such outward physiologic changes are easily measured, heavy exercise also sets off a complex cascade of biochemical activity that by all accounts is still poorly-understood.
There have been multiple theories for the actual cause of exercise-induced hematuria and proteinuria.  Gambrell and Blount (1996) discuss traumatic and non-traumatic origins, with the former thought to arise from either direct impact due to contact sports or from "shaking and jostling" associated with aerobic sports (1996).  The so-called "big three" exercises of powerlifting, however, seem to involve neither shaking nor impact to the region of the body containing the kidneys, unless one posits some mechanism whereby tightening lower back muscles exert pressure on the kidneys.
Recent studies have suggested the role of nitric oxide (NO) in glomerular permeability changes (Gündüz et al., 2003).  Whether NO plays a role or not, there is still no clear, overall mechanism established (Senturk et al., 2006).   Increased  permeability may depend on multiple factors;  at least one study suggests involvement of catecholamines (Poortmans et al., 2001).  Clonidine, a  catecholamine suppressant, was shown to reduce renal clearance of albumin by as much as 40% (2001).
Whatever the actual mechanism, the excretion of products that pass the glomerular membrane is undoubtedly affected also by other, less-hidden factors (e.g., amount of water ingested).  While the present experiment has suggested a difference between the sleeping and waking states on the morphology of urine sediments, this may depend partly on the fact that a sleeping test subject doesn't consume water or food.  Decreased water consumption inevitably leads to a more concentrated renal filtrate, which could explain the compactness of casts observed in the "sleeping" trial.  Subsequent experiments can clear this up if the "waking" subject(s) stop drinking water or eating food for the 8 hours leading up to collection of the "12-hour" specimen.  It remains noteworthy, however, that in both trials the maximum clearance of RBCs and / or hemoglobin through the kidneys happened at the same time relative to the strenuous exercise, regardless of the differences in food intake, water intake, sleep, movement, and other factors that existed between the two.  This suggests an intrinsic physiological and/or biochemical mechanism that is responsible for the time delay.


Gambrell, R. C., and Blount, B. W.  "Exercise-Induced Hematuria".  Am. Fam. Phys. 53(3):905-911 (1996 Feb. 15)

Gündüz, F., Kuru, O., and Senturk, U.  “Effect of Nitric Oxide on Exercise-Induced Proteinuria in Rats”. Journal of Applied Physiology 95: 1867-1872 (2003).

Poortmans, J.R. , Haggenmacher, C.,  and Vanderstraeten, J.  “Postexercise Proteinuria in Humans and its Adrenergic Component.”  J. Sport Med. Phys. Fitness 41(1): 95-100 (2001 March)

Senturk, U., Kuru, O., Kocer, G., and Gunduz, F.  "Biphasic Pattern of Exercise-Induced Proteinuria in Sedentary and Trained Men". Nephron Physiology 105(2): 22-32 (2006 Dec. 14).

Siegel, A.J., Hennekens, C.H., Solomon, H.S., et al.  "Exercise-related Hematuria. Findings in a Group of Marathon Runners. JAMA. 241: 391-392 (1979).

Strossen, Randall.  "Peary Rader (1909-1991)", Hardgainer, March 1992.

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