Influence of Breathing Technique on Arterial Blood Pressure During Heavy Weight Lifting

Transcription

1 457 Influence of Breathing Technique on Arterial Blood Pressure During Heavy Weight Lifting Joseph A. Narloch, MD, Murray E. Brandstater, MBBS, PhD ABSTRACT. Narloch JA, Brandstater ME. Influence of breathing technique on arterial blood pressure during heavy weight lifting. Arch Phys Med Rehabil 1995;76: Arterial hypertension occurring during heavy resistance exercise may be a risk factor for stroke in healthy young adults. Any training method that ameliorates the pressor effect of exercise should reduce the risk of stroke. The objective of this study was to observe the influence of breathing technique on arterial blood pressure (BP) generated during heavy, dynamic weight lifting. BP was recorded in 10 male athletes by radial artery catheterization. Each subject then performed double-leg press sets at 85% and 100% of maximum. Each exercise was performed twice, once with closed glottis Valsalva, and then with slow exhalation during concentric contraction. The mean BP at 100% maximum with Valsalva was 311/284. The highest pressure recorded in an individual was With slow exhalation, the mean BP was 198/175 when the same 100% maximum was lifted (p <.005). A reduced pressor response was also noted at 85% maximal lifting with slow exhalation. Arterial hypertension produced during heavy weight lifting with Valsalva is extreme and may be dramatically reduced when the exercise is performed with an open glottis (without Valsalva). It is concluded that heavy resistance exercise is safer when performed while the subject breathes with an open glottis by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation In acute hospital rehabilitation as well as outpatient programs, there are thousands of men and women across the United States who perform weight training and progressive resistive exercises as part of their daily physical therapy program. In addition, weight lifting has been avidly pursued by athletes and the general population with growing enthusiasm. However, some reports have described health risks associated with blood pressure (BP) elevation during heavy weight lifting. J-4 These risks include intracerebral hemorrhage. This study was initiated after two previously healthy, adult men were admitted to an inpatient rehabilitation unit after intracerebral hemorrhage. Both were recreational weight lifters who experienced an acute hemorrhage while performing vigorous resistance exercises at a fitness center. One patient was 38 years old and sustained an intracerebral hemorrhage near the middle cerebral artery. The other was 23 years old and sustained an intracerebral hemorrhage near the anterior cerebral artery. Neither patient had any predisposing medical conditions (such as hypertension) or took prescribed medications, illicit drugs, or anabolic steroids. Several other case reports have related hemorrhagic stroke and weight training. Tuxen and colleagues 5 reported on a 33-year-old veteran weight lifter who sustained a brainstem infarction during training. Hall-Jurkowski and associates 6 described a spontaneous subarachnoid hemorrhage that occurred in a 16-yearold girl during weight lifting. Frankle and colleagues v reported a 34-year-old male body builder who was actively From the Department of Physical Medicine and Rehabilitation (Dr. Brandstater), Loma Linda University Medical Center, and Jerry L. Pettis Memorial VA Hospital (Dr. Brandstater), Loma Linda; and The S.P.O.R.T. Clinic, Community Orthopaedic Medical Group, Department of Physical Medicine and Rehabilitation (Dr. Narlocb), Riverside, CA. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprint requests to Murray E. Brandstater, MBBS, PhD, Department of Physical Medicine and Rehabilitation, Loma Linda University, Anderson Street, Loma Linda, CA by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation /95/ /0 taking anabolic steroids and sustained a middle cerebral artery infarction during training. The incidence of acute stroke in otherwise healthy weight lifters is not known. In most cases identified in this review, including the patients in this study, no risk factors other than weight lifting were described. It is assumed therefore that the physiological stress of vigorous weight lifting may, in certain individuals, evolve into a state that places them at risk for a stroke. It is the authors' hypothesis that the physiological response that becomes a risk factor for stroke in weight lifters is arterial hypertension. The authors' proposed to study the arterial BP response during heavy weight lifting and whether a change in training technique could ameliorate the pressor effect of exercise. Only a few studies have investigated intra-arterial BP during weightlifting. Fleck and Dean s evaluated the pressor response in body builders versus novice weight lifters and found previous weight training experience reduced the pressor response. This was determined only with single-arm overhead presses and one-leg knee extensions. Lewis and colleagues 9 examined the BP response in relation to the amount of muscle mass exercised and mode of contraction. They found that when larger muscle mass groups performed isotonic exercise, a higher BP was generated in comparison to that observed with smaller muscle mass groups. MacDougall and associates 1 measured the BP response in weight lifters with Valsalva being performed against a mouthpiece and not with a true closed glottis technique. They found extreme pressures (up to 480/350 mmhg in one subject). No published data is known comparing the intra-arterial BP response during dynamic muscular contraction with and without a Valsalva's maneuver. The first objective of this study was to confirm the previous observations of extreme arterial hypertension during heavy isotonic resistance exercises. Secondly, it was hoped that a safer method for performing heavy resistance exercises could be established in which the increase of BP would

2 458 BLOOD PRESSURE DURING WEIGHT LIFTING, Narloch ~ Pruef ~ s(~r~ OI nfla~gr~ M... Uy- TMUabneo m e t e r T oampfer ~ 114 TuSlurggical 2 Recorder ~ = ~ r ~ Bvle,eder jb "~" ~n'--'--~ Pressure Generating 250 cc I II ~I1 r Bulb with Valve Heparinized Kelly Clamp sa,,oo I LJ-LJ I tj i ~ IHI ~' ~'~- Water Column Dome Pressure ~ 3-Way ~ ' 22 Gauge Transducer Damper Stop Cock Angiocath Fig I IA schematic illustration of the BP monitoring system an intra-arterial pressure recording system. Features include the U-tube manometer for calibration and the adjustable air column for critical damping. be less. In the gymnasium, many athletes lift weights with Valsalva's maneuver (closed glottis) during peak effort. The hypothesis to be tested was that the increase of BP would be less if the exercise was performed with slow exhalation (open glottis) rather than with closed glottis Valsalva. MATERIALS AND METHODS Ten healthy male athletes, ages 25 to 35 years, responded to an advertisement and volunteered for the study. The group consisted of five body builders, three cyclists, and two runners. All of the subjects used free weight training as part of their regular workout at least three times a week. A screening history was taken to exclude persons with hypertension, cardiac abnormalities, and bleeding disorders. None of the athletes used any prescription medications, anabolic steroids, or growth hormones. Before catheterization each subject was examined with the Allen's test 11 in his nondominant wrist to ensure the safety of the subjects. The Allen' s test consists of the examiner applying pressure with his fingers to occlude blood flow in the subject's radial artery. The examiner then palpates the pulse in the ulnar artery of the subject and looks for signs of cyanosis in the hand. A subjective evaluation is then made as to whether the pulse and therefore blood flow in the ulnar artery could adequately perfuse the hand if the radial artery were permanently occluded. The nondominant radial artery was cannulated by a staff anesthesiologist with a 22-gauge Angiocath a at the wrist. The catheter was flushed with heparinized saline. The wrist was then immobilized by taping the hand and forearm to a padded rigid catherization splint (commercially known as a Lundy boardb). This was performed to prevent hand and wrist movement that might have contaminated the pressure readings. The catheter was connected to a pressure transducer with a disposable transducer dome via a heparinized saline line. The transducer was adjusted to the height of the sternal notch for each subject. The transducer was attached to a multichannel monitor/recorder. Before each usage, the system was calibrated using a pressure bulb and a U-tube manometer (fig 1). The pressure recordings were verified to be linear within the range of 0 to 500mmHg. The system was initially undamped. With abrupt changes in pressure, the recording showed an overshoot followed by a brief resonating wave. Correction of this problem was achieved by incorporation of a damping device into the line consisting of a compliant length of closed surgical tubing. At the optimal level of damping, which was obtained by adjusting the amount of air in the tube, there was virtually no overshoot or resonance, and the frequency response was adequate (fig 2). The exercise performed was a leg press on a Universal Gym ~ using both lower limbs simultaneously. Before catheterization, the maximum amount each subject was able to lift, for a set of five repetitions, was determined. Each subject was catheterized and attached to the monitoring devices. The resting blood pressure was then recorded. Each subject was then asked to Valsalva at rest for a period of 2 seconds. This resting Valsalva was repeated five times in succession. Closed glottis Valsalva was verified by using nose plugs and a spirometry whistle that indicated when exhalation occurred. A total of four sets of isotonic leg presses were performed by each subject with a 5-minute rest period between each set. In the first set, the subject lifted, to the point of concentric contraction fatigue, 85% of his maximum five repetition set using Valsalva during concentric muscle exertion. The second set was performed using the same weight, to the point of concentric contraction fatigue, while avoiding Valsalva by maintaining slow exhalation on exertion (as verified by the spirometry whistle). The third and forth sets were performed as the first two, except the weight lifted was increased to 100% of each subject's maximum five-repetition set. No pausing was allowed between repetitions within a set, with each set lasting no longer than 15 seconds. During the exercise, the subject's catheterized arm was rested on a stool and immobilized by an arm splint so as not to artificially elevate the readings. The contralateral arm was used for balance and support on the leg press chair. The maximal blood pressure (systolic and diastolic) during each set was recorded for each individual. The mean of the maximal blood pressures from all the subjects was compared when slow exhalation was used versus Valsalva during concentric exertion. The comparison was made at both 85% and 100% maximum weight lifted. The data were analyzed using a student t test. RESULTS The peak levels of BP for all subjects are tabulated in the table. The mean peak BP recorded for both diastolic and A. B. C. 500 E,~ i=~,1~ ~ i i...' 400 ' i!~::~,~::'~i~ =1~!'~ 400 ~ o o / E ~ ~ I' ~ilii, ~ ~ ~ -, i'=,,,',,'e':' 200 I I:~']~'[~L ~ ~ ; E 100 t~~;~ 100 ~ 100 ~ ~ 0 ~!14;i!!['i? ' H' ii~[iy!j II 0!~' ;4 i?~lii~!t;ii~l~.~ll~ i : I '~Hil![t't~~!!I ~,irl,,i ~111 hi[,it,]~'~ Time ~ I.~ 0.1 sec Fig 2--System response to dampening. (A) An underdamped signal of 300mmHg with false maximal elevation and hyperresonance in the recording. (B) The same signal is overdamped with delayed arrival to maximum pressure. (C) The signal is critically damped with adequate pressure recording.

3 BLOOD PRESSURE DURING WEIGHT LIFTING, Narloch 459 Subject Data of Maximal Blood Pressure (BP) 85 % 85 % 100 % 100 % Resting BP Exercise Exercise Exercise Exercise Subject Resting BP VALSALVA Breathing VALSALVA Breathing VALSALVA l 100/60 130/ / / / / /90 200/ / / / / /70 200/ / / / / /70 170/ / / / / /30 200/ / / / / / / / / / / /70 140/ /90 200/ / / /70 210/ / / / / /90 180/ / / / / / / / / / /360 Average 127/82 180/ / / / /284 NOTE. BP readings at rest and peak values during exercise using Valsalva's maneuver and open glottis technique. systolic is shown in figure 3. The mean BP increased substantially with Valsalva in comparison to slow exhalation when at rest or, most conspicuously, with 85% and 100% maximum lifting (p <.005). Levels of BP generated were higher with 100% maximal lifting in comparison with 85% for both Valsalva and slow exhalation (p <.025). Actual BP traces of a subject are shown in figure 4. The resting BP of 140/110 and a heart rate of 84 is observed in tracing A. Tracing B shows the wavering of BP to a high of 190/170 and a low of 140/120 with Valsalva. The heart rate is measured at 78. With 100% maximal leg press and slow exhalation, BP quickly increased with each contraction on the press (tracing C). The pressure increases to a maximum of 220/200 with contraction and decreases to 170/150 with relaxation. Heart rate increased to 132. In tracing D, the pressure with 100% maximal lift and Valsalva shows a peak pressure of 370/360. The peak pressure was achieved on the fourth repetition of the set and stabilized within 50mmHg of the subsequent repetitions in the set. Heart rate also increased to 186. The rise slope in the pressure tracing 400 O) -r- E 300 E 200 -(3 O 100 o nn [] Slow Exhalation [] VALSALVA ~ 0 12[~ ± ls5 82 J- J_ 156 ~ 7 7a ± 2a,, 175 Resting 85% Maximal 100% Maximal Weight Lifted Weight Lifted Fig 3--BP during exercise: with and without Vaisalva. Mean maximal BP, systolic and diastolic, at rest and with 85% and 100% maximal leg press lifting. In each case, pressures generated with Valsaiva are significantly higher (p <.005) than with slow exhalation. Resting average pressures are 127/82 versus At 85% they are 178/156 and 267/239. Mean pressures peak at 100% maximum lifting at 198/175 with slow exhalation at 311/284 with Valsalva. is much steeper with Valsalva in tracing D than in tracing C. Systolic pressure wavers by approximately 120mmHg between the repetitions of tracing D. The tracing patterns observed in these particular readings are typical of all the subjects studied. The elevated BP returned to the pre-exercise resting baseline within 2 to 3 seconds after the last repetition was completed. DISCUSSION One objective of this study was to document the extreme blood pressures which could be generated during isotonic weight lifting. MacDougall and colleagues 1 observed that BP increased higher when a double-leg press was used versus a single-leg press, and when a single-leg press was used versus a one-arm curl. It has been postulated that absolute muscle size and force of contraction correlate with BP elevation. The double-leg press exercise was therefore selected because it involves the largest and strongest muscles in the body and would generate the highest physiological change in BP. The extreme BPs observed during heavy resistance exercises are surprising, but their physiological basis can be predicted given the underlying mechanisms involved. It is evident (fig 4) that the increase in BP is closely associated with actual muscle contraction and/or duration of Valsalva: The increase in BP begins abruptly, increases gradually, and the BP begins decreasing immediately after the action ceases. The cardiac output, Q, is the product of heart rate and stroke volume (SV), and BP is proportional to the product of Q and the total systemic peripheral resistance. Thus, changes in BP are achieved by alterations in heart rate, SV and/or peripheral resistance. The arterial pressures recorded with and without Valsalva increased to extreme levels when heavy weight lifting was attempted. Valsalva combined with weight lifting appeared to have a synergistic effect, elevating blood pressure to supertensive levels. These data were similar to those found by MacDougall. l Transient pressures above 250mmHg are probably within the normal physiological range of all individuals performing heavy lifting tasks with Valsalva. The primary mechanism behind the pressure increase is probably a combined effect of the reflex pressor response, Valsalva's maneuver, and mechanical muscle compression. The observation of a reflex pressor response to sustained somatic muscle contraction was first described by Alam and

4 460 BLOOD PRESSURE DURING WEIGHT LIFTING, Narloch A. B. C. D. ~n 400 ~ o 100 o 0 5 m Time ~ I--I 1 sec (Resting) Heart Rate 84, max BP "1" 40O aoo EE loo { Q (VALSALVA alone) Heart Rate 78, max BP 190/ I- 400 ~ " ' -ff: 300 ~- 200 ~ - - ~ = ~oo 17 ;,?iii :~ ;71iiN O ::ii... 50o "i- 400 E 300 E 200 m 10o o (Exercise alone) Heart Rate 132, max BP 220/200 ~ F T[~ ;i r: I i::l::~,,..... Ih H!;il!!1! i!i :!1'.! ~:lil :.;:] i:n Iii (Exercise & VALSALVA) Heart Rate 186, max BP Fig 4--Effects of exercise and Valsalva. BP tracings of the same subject at (A) rest, (B) rest with Valsalva, (C) 100% maximal leg press with slow exhalation, and (D) 100% maximal leg press with Valsalva. Smirk. 12 When a muscle contracts, signals are received by the cardiovascular centers in the brain. These are sent by receptors in the muscle that respond to metabolic changes associated with contraction and mechanical vascular constriction ~3 (fig 5). The afferent impulses are conducted via small myelinated and nonmyelinated fibers (groups III and IV) ~4 and ascend via the spinothalamic tract to the cardiovascular centers. The reflex response consists of the following: (1) reduction of parasympathetic vagal tone to the heart, increasing the heart rate and (2) increased sympathetic noradrenergic outflow leading to enhanced cardiac contractility, contraction of the visceral vascular beds (as well as nonexercising somatic vessels), and the release of epinephrine from the adrenal medulla. As BP increases, the baroreceptors in the carotid sinus and aortic arch cause vagal stimulation to modulate the BP. However, in the muscle pressor response, the baroreceptors are inhibited ~5 and placed at a higher set point so as not to interfere. In addition to peripheral feedback, there are connections from the motor cortex to the cardiovascular centers that directly facilitate adrenergic activity. ~6 In the present study, greater effort by the subjects generated higher peak BP levels. The elevation of the BP was greater at 100% in comparison with 85% maximum lifting. The mean peak pressures with Valsalva were elevated to 237% of resting levels at 100% maximum lifting versus 204% at 85% maximum lifting (311/284 versus 267/239 mean peak BP, see table 1). A similar trend was observed with slow exhalation, the mean peak BP being 150% versus 136% of resting levels, respectively. It is likely that the mechanisms responsible for BP elevation in these experiments were in large part related to the force produced by the muscle during contraction. Valsalva's maneuver involves the closing of the glottis after inspiration followed by an expiratory effort. It occurs normally during coughing, pushing, lifting, vomiting, and defecation. The BP and heart rate changes that occur during Valsalva were first described by Port and associates. ~7 The physiological changes may be divided into four sequential phases. Phase I begins with the onset of strain, during which there is an abrupt increase of both systolic and diastolic pressure caused by transmission of intrathoracic and intra-abdominal pressures to the left heart and aorta./8 Heart rate remains the same or may increase slightly during this phase, which lasts 3 to 4 seconds. Phase II begins as SV drops because of decreased venous return. The BP begins to decline, and there is accompanying baro-reflex-mediated increase in HR and peripheral vascoconstriction. Blood pressures fall below resting levels within 10 to 15 seconds of Valsalva. 19 Phase III starts immediately on termination of the strain. The arterial pressure decrease in a precipitous manner as intrathoracic pressure decreases. This phase lasts only for a few heartbeats as venous flow rapidly fills the right heart. Phase IV is known as the "overshoot" phase. SV is augmented, whereas the peripheral resistance remains elevated. / (~ Hyperemic Humoral + / i.ep,ne...ne CONSTR'OT'ON OF S"LANCRM'C1 l--r I --1 I KIDNEY AND RESTING MUSCLE I i---> I I ARTERIOLES I ~ / Fig 5--A schematic representation of the reflex pressor response where by muscle action initiates and controls subsequent increases in BP.

5 BLOOD PRESSURE DURING WEIGHT LIFTING, Narloch 461 Blood pressure increases and remains elevated for 3 to 8 seconds after strain is released. The overshoot is quickly resolved with bradycardia secondary to baro-reflex-mediated vagal output. Valsalva performed during repetitive resistive exercises is altered from the above classic description. During each repetition the closed glottis strain is only held for 3 to 5 seconds. This would normally be at early phase II. However, with resistive exercises, phase I is prolonged by the mechanical pump action of the contracting peripheral muscles. Venous return is thereby facilitated despite the initial increase in the intrathoracic pressure. Thus the Valsalva strain is terminated at the end of phase I. Phases II and III, which are the hypotensive phases, do not occur with repetitive resistive exercises. Because short episodes of Valsalva only involve phase I and IV, blood pressure is augmented throughout the repetitions. This explains the increase in the BP with repetitive straining alone without exercise. Similar elevation and maintenance of BP has also been observed with sustained Valsalva by Hughes and colleagues 19 using hand grip exercises. In most of the subjects in this study, BP increased slightly as the set progressed. The highest BPs were observed with one of the final repetitions. Williams and Lind 2 observed a similar gradual increase in BP with repetitive hand grip exercises. This observation was observed in these subjects, both with and without Valsalva. The increasing pressure is therefore probably caused by the increased reflex pressor response related to enhanced muscle contractile effort with fatigue. An example of this is shown in figure 4 where the resting baseline BP in this normotensive subject was elevated, representing a pressor effect from previous exercise. The increase in mean peak BP recorded during slow exhalation was dramatically less than the increase when exercise was performed with Valsalva. The difference in systolic BP was increased by ll3mmhg (198 v 311) with 100% maximum lift. The weight lifted and number of repetitions were not changed between the Valsalva and slow exhalation sets. At 85% maximum lift, systolic BP increased 89mmHg less with slow exhalation versus exercising with Valsalva. The synergistic effect of Valsalva and heavy resistive exercises in BP elevation appears clear. Mechanical muscle compression is another synergistic factor of extreme BP elevation. Intramuscular pressures generated during exercise can be quite large, up to 1,000torr in the quadriceps. 21 With pressures lower than 1,000torr, intramuscular arterial flow is occluded and peripheral resistance is increased. The larger the muscle group involved with the exercise, the greater will be the effect of muscle compression on systemic BP. However, the overall effect of muscle compression is not great, because BP will increase almost as much when one leg is exercised compared with two legs. 2 To what degree BP increases in patients whose rehabilitation program includes vigorous resistance exercise has not been assessed as yet. The pressor response in heavy weight lifting is reported to be the same among young, older, and elderly men who performed isotonic dead lifts. 22 It can be assumed that although the majority of the rehabilitation and disabled population is significantly older than the study subjects, they too have significant increases in blood pressure with weight lifting. Certain categories of rehabilitation patients such as paraplegics participate in resistance exercise of comparable intensity to that performed by these subjects. It is not known whether generation of extreme BPs during weight lifting on a frequent and regular basis influences resting BP levels or contributes to sustained systemic hypertension. However, the avoidance of Valsalva during weight training would obviously reduce the probability of intracranial hemorrhage in the disabled population at risk, eg, those with history of stroke, cranial surgery, or hypertension. CONCLUSION Arterial BP may more than triple during heavy resistive exercise compared with resting levels. High BP levels are observed when subjects simultaneously perform Valsalva's maneuver as they exercise. Such high BP levels could represent a risk factor for cerebral hemorrhage in certain individuals. Exercise-induced hypertension could have been the cause of stroke in the two case subjects who were otherwise healthy. The physiological studies in normal subjects have shown that with elimination of Valsalva, maximum BP is substantially reduced. It is the authors' hypothesis that elimination of the Valsalva during heavy resistance exercise would reduce the risk of stroke. References 1. Basford JR. Weight lifting, weight training and injuries. Orthopedics 1985;8: Breall WS. Risks of weight lifting. JAMA 1985;212: Hunter GR, McCarthy JP. Pressor response associated with high intensity anaerobic training. Physician Sports Med 1983; 11: Legwold G. Does weight lifting harm a prepubescent athlete? Physician Sports Med4982; 10: Tuxen DV, Sutton J, MacDougall D, Sale D. Brainstem injury following maximal weight lifting attempts. Med Sci Sports Exerc 1983; 15: Hall-Jurkowski J, Sutton JR, Duke RJ. Subarachnoid hemorrhage in association with weight lifting. Can J Sport Sci 1983;8: Frankle MA, Eichbewrg R, Zachariah SB. Anabolic steroids and a stroke in an athlete: case report. Arch Phys Med Rehabil 1988;69: Fleck S J, Dean LS. Resistance-training experience and the pressor response during resistance exercise. J Appl Physiol 1987;63: Lewis SF, Snell PG, Taylor WF, Hambra M, Graham RM, Pettinger WA, et al. Role of muscle contraction mass and mode of contraction in circulatory responses to exercise. 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Heart Lung 1984; 13: Mantysaari M, Antila K, Peltonen T. Relationship between the change

6 462 BLOOD PRESSURE DURING WEIGHT LIFTING, Narloch in heart rate and cardiac output during the Valsalva maneuver. ACTA Physiol Scand 1984;Suppl 537: Hughes L, Heber M, Lahiri A, Harries M, Raferty E. Haemodynamic advantage of the Valsalva maneuver during heavy resistance training. Eur Heart J 1989; 10: Williams C, Lind A. The influence of straining maneuvers on the pressor response during isometric exercise. Eur J Appl Physiol 1987;56: Seals D, Washburn R, Hanson P, Painter P, Nagel F. Increased cardiovascular response to static contraction of larger muscle groups. J Appl Physiol 1983;54: Salgiv D, Ben-Sirq J, Rudoy J. Cardiovascular response during isometric dead lift in young, older and elderly healthy men. Int J Sports Med 1988;9: Suppliers a. 22-gauge Angiocath; Becton-Dickinson Vascular Access, Sandy UT b. Lundy board; Medline Industrial, Inc., 1 Medline Place, Mundelein, IL c. Universal Gym, th Avenue, SW, Cedar Rapids, IA