Applications of Breath-holding from Free Diving to Kayaking - Mountain Buzz
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Applications of Breath-holding from Free Diving to Kayaking
One of the things I've considered as I've trained as a kayaker is that I'd really like to be able to hold my breath for a long long time.
I thought this article about free diving was very interesting and informative:
While the stuff about water pressure is super interesting but obviously doesn't apply to our sport, I thought the insights into breath-holding were very interesting.
I assume that with many drownings, water is &breathed& before unconsciousness is reached.
I wonder if, with a little training, perspective, and zen we couldn't go a lot lot longer without breath while waiting for that hole to flush or that rope to come.
Prinsloo was waiting for me on the shore of Crystal River in Florida, a lush nature reserve on the Gulf of Mexico. She now runs a nonprofit conservation group, I Am Water, and was gathering documentary footage on manatees, which congregate in the area’s naturally warm springs during the cold winter months. She had suggested I join her and insisted she could teach me to hold my breath like a free diver in one lesson.
As the sun ascended, we hopped in sea kayaks, paddled down the river for half a mile, tied them up the shore, and splashed into the water. I duck-dived beneath the surface and followed Prinsloo to a 10-foot-long manatee with its paddle-like flippers, elephantine skin, and cow-like snout. It regarded us passively through small button eyes as we all floated several feet beneath the surface together in silence, slowly bobbing in silence with rhythm of the gentle, morning tide. As I surfaced, panting for air, I watched Prinsloo stay underwater with perfect calm. Clearly I had a lot to learn.
Prinsloo and I paddled back to shore and found a quiet spot on a grassy knoll. Kneeling in front of me, she told me to lie down and close my eyes. “Breath deep, slow down, realize that we tell ourselves stories, and tell yourself a good one,” she said. She then led me through three breath-holds, promising that by the third one I would be amazed by how long I could hold my breath.
The first breath was the “feel-good breath-hold.” She asked me to relax, hold my breath in a state of near sleep, and wait until I felt a “trigger” that snapped me back to something approaching awareness and signaled the nonverbal version of, “What the hell? This is too long. You need to breathe!”
For the second breath-hold, Prinsloo instructed me to go beyond this “trigger point” and continue to hold my breath until my diaphragm started to contract. Finally we reached the third hold. For this one, Prinsloo instructed me to observe the trigger, but keep holding, to feel the contraction, and press on.
“Let the contractions come and go,” she advised me. “They don’t go away, they don’t get any better, they just are, so you just try to keep relaxing and let whatever happens happen. Just let them move. It’s almost like a wave when they start coming.”
I placed my hand on my stomach, and continued to hold my breath. It wasn’t so bad. In fact, I felt a stillness, time seemed to stop. For a few moments, I was profoundly aware of the world around me. The splashing from a distant pool, the sound of people chattering as they walked nearby, the sun on my face. Then I could hold my breath no longer.
After I exhaled, Prinsloo revealed my times and they shocked me. My first breath hold lasted for 1 minute 45 seconds. My second was for 2 minutes and 50 seconds. On my third attempt, I held my breath for almost 3 minutes and 45 seconds. I had more than doubled my time by following Prinsloo’s simple instructions.
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San Jose, CA, California
Paddling Since: 1998
Join Date: Apr 2008
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That is awesome!
Preacher of the Profit
Paddling Since: 1990
Join Date: Oct 2003
Posts: 1,065
I think you are confused.
Holding your breath is very much part of &Our& sport.
Many whitewater kayakers are still avid squirt boaters.
Where exercise, kayaking, and breath management are very much all in play.
Check it out:
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Carbondale, Colorado
Paddling Since: 1965
Join Date: Jan 2010
Posts: 189
When I was young I practiced holding my breath a lot - mostly just because I was bored in school etc. Got to where I could go three minutes. I can point to several instances where this ability came into play and perhaps saved my life but for sure gave me the confidence not to panic and just let the river flush me out of a bad situation knowing that I had a lot of time left. The other part of the equation is knowing when to fight and when to relax.
Denver, Colorado
Paddling Since: 2002
Join Date: Feb 2012
Posts: 670
Rock running is a way surfers develop their breath holding abilities. It's one thing to remain motionless and hold your breath it another to hold your breath while exerting yourself physically.
Squirt boaters call themselves zombies because a long day of cold water and deep mystery moves makes your body number, tingling, slow, and a bit disembodied
Denver, Colorado
Paddling Since: 2011
Join Date: Jul 2012
There are many apnea training apps for both android and iPhone. It is a proven methodology for expanding lung capacity.
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Preacher of the Profit
Paddling Since: 1990
Join Date: Oct 2003
Posts: 1,065
That's not why squirt boaters call themselves zombies.
It's because of them coming up from under water.
Just like a zombie coming out of the ground.
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I love to dance, but who needs the music- It throws me off.
Denver, Colorado
Paddling Since: 2002
Join Date: Feb 2012
Posts: 670
Don, It appears we are both correct.
&Practitioners are sometimes called zombies because they go in druid-like circles all day pursuing bubbles and become entranced by sparkly water and metalflake- and they don’t walk so well because their feet have been cramped in a boat hardly bigger than a ballerina slipper. & - Jim Snyder
I've seen him write elsewhere that the hyperventilating and then long periods of breath holding make you become numb, like your extremities are dead.
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]. A small scatter fraction with maximum sensitivity was achieved by optimizing the collimator gap for the 99mTc source. The system was attached to an opposing two-headed detector with low-energy, high-resolution (LEHR) collimators, as shown in Figure A. The TCT source consisted of a 3-m long tube (5 mm in diameter) filled with 740 MBq of 99mTc, which was equivalent to seven separate rod sources. Each rod was collimated axially with lead sheets. The TCT system was removed from the SPECT detector before the following scans.
Experimental setup. (A) Schematic diagram of 99mTc transmission system attached to a SPECT/CT detector. (B) and (C) System to monito (B) optical motion-tracking device. (C) Infrared-reflective target placed on the subject’s abdominal surface.
After acquisition of a CT scout image, breath-hold CT-AC scans were performed at the INS, EXP, and MID respiratory phases. CT acquisition parameters were as follows: helical scan time, 10 rotation cycle, 1 pitch, 1.0; tube voltage, 130 kVp; tube current, 100 mA over 10 slice thickness, 5 slice interval, 5 matrix size, 512 × 512; pixel size, 0.98 × 0.98 mm2; and maximum duration for holding breath, 16 s. For breath-hold CT acquisition at each phase, a system of monitoring and displaying respiratory phase was introduced. Briefly, a subject’s abdominal respiratory motion was determined using an optical motion-tracking device, POLARIS (Northern Digital Inc., Ontario, Canada), to monitor the location of an infrared-reflective target placed on the abdominal surface, as shown in Figure B,C. The accuracy of the device was 0.35-mm root mean square (RMS), as reported by the manufacturer. The motion was displayed on a screen using an ellipsoidal indicator to enable the subject to control his or her own breathing in real time. The subject breathed deeply several times to determine the marker’s range of motion between the EXP and INS phases before the CT-AC scans. The MID phase was defined as occurring when the marker was located at the central position of the motion range.
Dynamic SPECT begun 2 min before the start of the 2-min constant infusion of 111-MBq 201Tl. Projection data were acquired using the detector heads positioned opposing each other (H-mode) with the LEHR collimators in continuous mode and in a circular orbit because QSPECT reconstruction was performed on geometric-mean projections. The frame collection rates and 360° rotation times were 6 × 2 min (28 s) and 8 × 5 min (148 s); number of views, degrees per view, matrix size, and enlargement factor were 45 views, 4° per view, 64 × 64, and 1.45, respectively. A 34% energy window centered on 77 keV was used for the 201Tl acquisitions [, ].
SPECT projection data were processed to generate a quantitative image, that is, pixel values were calibrated in Bq/mL. The procedure was as follows: (1) TCT projections normalized by blank projections and CT projections were reconstructed and then linearly scaled to provide attenuation maps for 201Tl. For CT images, filtering to SPECT spatial resolution using the B08s filter, which was called by the manufacturer, interpolation to equate the matrix and pixel sizes to those of TCT attenuation map, and conversion from Hounsfield units to attenuation coefficients were performed using Syngo MI Application, version 7.0.7.14 (Siemens, Knoxville, TN, USA). (2) A SPECT image was temporarily reconstructed using a filtered backprojection algorithm without scatter or attenuation correction. Each attenuation map was manually aligned to the SPECT image using translations along three orthogonal directions by interactively moving the attenuation map image over the SPECT image. The interactive fusion was performed using the QSPECT software package. The overlap in the aligned images was assessed in coronal, sagittal, and transaxial views based on the distances of myocardial contours between the anterior to lateral regions of the attenuation map and the SPECT images. (3) Using each alignment parameter, scatter- and attenuation-corrected images were reconstructed with OSEM (three iterations, five subsets using geometric-mean projections, post-reconstruction Gaussian filter of 7.0 mm in full width at half maximum) provided by the QSPECT software package [], respectively.
Each dynamic image reconstructed using the four attenuation maps was summed into a static image with the 14.5- to 34.5-min frames (mid-scan time). Transformation to a short-axis orientation was based on a static image corrected with a TCT attenuation map (TCT-AC image). The transformation was also applied to the static images corrected with CT attenuation maps (CT-AC images). The radioactivity concentrations of the images were normalized by the subject’s weight. Variability of normalized radioactivity concentrations in the myocardium was also assessed. Polar maps for the left ventricles were generated from the static images. In this process, the basal slice and apical region were defined on the TCT-AC image. The definition was also used for the CT-AC images of the same subject. In addition, percent differences between the weight-normalized radioactivity concentrations of TCT-AC and CT-AC images were calculated as
. Regional radioactivity concentration values and percent differences were evaluated for myocardial segments by dividing polar maps into 17 segments according to the AHA 17-segment model []. To evaluate the effects of attenuation correction with the four attenuation maps on SPECT images, the regional radioactivity of TCT-AC and CT-AC images was statistically tested using the Tukey multiple comparisons method. Homogeneity of radioactivity distribution among the 17 myocardial segments was also assessed using the Tukey multiple comparisons method for each dataset of TCT-AC and CT-AC images. A p-value of less than 0.05 was considered statistically significant.
Breath-hold CT-AC scans at three respiratory phases were performed successfully for all subjects. The amplitude of the marker indicating respiratory phases, which was defined as half the distance between the infrared-reflective targets at the INS and EXP phases, was 8.50 ± 5.58 (2.51 to 17.50) mm. Translations to align attenuation maps to SPECT image was listed in Table . Cephalad/caudal translations were dominant among three orthogonal directions, especially in CT attenuation maps at the MID and the EXP phases. Figure
shows examples of TCT and CT attenuation map images at the three phases. In coronal and sagittal views at the INS phase, the surfaces of the inferior regions of the myocardium and the liver were clearly separated. On the other hand, at the EXP phase, it was difficult to distinguish these surfaces. The position of the heart relative to the liver at the MID phase seemed to be similar to that of TCT attenuation map rather than those at the other respiratory phases. Figure
shows SPECT images for the same subject as Figure . The left, middle, and right columns represent slices at basal, middle, and apical levels, respectively.Table 1
Translations to align attenuation maps to SPECT image (mean ± SD)
TCT0.0 ± 0.00.0 ± 0.02.4 ± 2.1CT at MID2.8 ± 7.1-2.6 ± 3.911.7 ± 8.0CT at INS4.5 ± 6.0-4.7 ± 5.46.2 ± 7.3CT at EXP-1.5 ± 3.50.0 ± 5.119.9 ± 5.8
Attenuation map images of
Tc-TCT and CT at three different respiratory phases. The left, middle, and right columns represent transaxial, sagittal, and coronal views, respectively.
SPECT images corrected for attenuation and scatter using TCT and CT attenuation maps. The left, middle, and right columns represent slices at the basal, middle, and apical levels, respectively. The subject was the same as in Figure .
The distribution of weight-normalized radioactivity concentration and the differences between TCT-AC and CT-AC images are shown in Figure . The left column displays polar maps of averaged radioactivity concentration, normalized using the maximum value of the TCT-AC map. Statistical analysis of the SPECT image datasets with the four attenuation maps indicated that the images corrected with EXP attenuation maps were different significantly from the other datasets, that is, significant differences in weight-normalized radioactivity concentrations were observed between TCT-EXP, INS-EXP, and MID-EXP image datasets (there was no significant difference in weight-normalized radioactivity concentration between TCT-INS, TCT-MID, and INS-MID). No regional differences were found in weight-normalized radioactivity concentrations of any datasets, although relatively large values in inferior regions were observed for all TCT-AC and CT-AC image datasets. As shown in the right column, the polar map of the percent difference for CT-AC images of EXP phases shows a positive bias, 5.7% ± 2.7% (1.9% to 10.0%), over all segments. Regional tendencies were found for CT-AC images of the other two phases: for the anterior to anterolateral segments, positive biases of 5.0% ± 2.2% (1.3% to 8.1%) and 5.6% ± 1.9% (2.6% to 8.5%) and for the inferior to inferoseptal segments, negative biases of -5.3% ± 2.6% (-9.1% to -1.7%) and -4.6% ± 2.5% (-8.8% to -1.5%) for the MID and INS phases, respectively. The worst segmental percent differences (mean ± SD and the worst individual value) were 10.5% ± 4.9%, 22.6% in the basal inferolateral segment for the EXP -4.8% ± 4.8%, -11.0% and -8.0% ± 6.4%, -18.4% in the mid inferior segments for the MID and the INS phases, respectively. The percent difference excluding the worst individual value was 9.3% ± 3.0% in the basal inferolateral segment for the EXP phase. It was considered that the relatively large differences in radioactivity concentrations of the EXP polar map, as shown in Figure , compared to the MID or the INS polar maps were due to the results over all subjects, but was not from outliers.
Polar maps of averaged radioactivity concentrations and percent differences from images corrected with TCT attenuation maps.
This study investigated the effects of respiratory phases on breath-hold CT-based attenuation correction in cardiac SPECT with monitoring of the respiratory phase and amplitude. Reconstruction using CT attenuation maps at the INS and MID phases, with correction for attenuation and scatter, provided quantitative SPECT images that agreed with images derived from TCT-based attenuation maps. The SPECT images with CT attenuation maps at INS and MID phases showed similar radioactivity concentrations, as seen in Figures
and . This may be due to similarities between CT attenuation maps at INS and MID, for instance the separation between the surfaces of the inferior myocardial wall and the liver, as shown in Figure . Polar map analysis of the four attenuation maps showed no significant heterogeneity in any image dataset in terms of weight-normalized radioactivity concentrations.The CT-AC images corrected with EXP attenuation maps differed significantly from the TCT-AC and CT-AC image datasets at INS and MID phases. In addition, for all segments, the percent differences from TCT-AC images indicated a bias of CT-AC images with EXP attenuation maps: a positive bias in anterior to anterolateral segments and a negative bias in inferior to inferoseptal segments for CT-AC images with both INS and MID attenuation maps, as shown in Figure . The magnitude of the bias for CT-AC images with EXP attenuation maps was larger than that of CT-AC images with the other respiratory attenuation maps. As previously reported, MBF was non-linearly related to the radioactivity concentration for 201Tl kinetics [, ]. Error with positive bias in the concentration propagated to error in MBF values more than negative bias with the same magnitude. Therefore, we considered the CT attenuation maps at the INS or MID phases to be preferable to those at the EXP phase. Instead of breath-hold CT acquisitions, respiratory gating in both SPECT and CT scans was expected to be another approach for CT-AC. Uniformity of radioactivity concentrations in myocardia has been improved by respiratory-gated SPECT acquisition []. Although respiration-related artifacts must be corrected ideally, the breath-hold CT-AC might be suitable for dynamic SPECT studies with low-dose injections, such as measurement of absolute MBF, which needed temporal changes in radioactivity concentrations.Although no significant heterogeneity in regional radioactivity concentrations was observed, Figures
show reduced radioactivity concentrations in the anterior regions near the apexes and increased concentrations in the inferior regions in images with all attenuation maps. Potential reasons for the reduced concentrations are as follows: first, residual errors in registration between an attenuation map and a SPECT image. Fricke et al. reported that a 3.5-mm misalignment in the ventrodorsal direction induced a spurious defect in the anteroseptal wall in a phantom study []. The second reason is spillover from the anterior wall due to partial volume effects. The anterior wall was surrounded by void space in terms of 201Tl concentration. Spillover from the wall, particularly near the apex, could be affected by the partial volume effects three-dimensionally. In contrast, possible reasons for relatively high concentrations in the inferolateral to inferior wall are as follows: (1) residual errors in registration as seen with the anterior wall, (2) overestimation of attenuation effects around the inferolateral to lateral walls caused by the liver, as pointed out by Cook et al. [], and (3) spillover from other organs. Little effect of overlap between the heart and the liver was reported by McQuaid and Hutton []. However, in their numerical phantom study, spatial resolution effects of a SPECT scanner were excluded, and the assumed activity ratio between the myocardium and the liver was 75:30. Their experimental conditions were different from those in our human study, specifically the spatial resolution of the SPECT scanner and the activity ratio of the two organs (liver/anterolateral myocardium = 1.1 ± 0.3, range = 0.7 to 1.7). High radioactivity concentration was also observed in the left kidney (the activity ratio of the left kidney/anterolateral myocardium = 1.5 ± 0.3, range = 1.1 to 2.0). It could cause additional spillover to the anterolateral myocardium. Anatomical information from the CT image prior to spatial resolution matching to SPECT was expected to help correct for the spillover and, thus, produce a more accurate quantitative SPECT image.In this study, the use of CT-AC attenuation maps with breath holding was validated at resting conditions. In order to measure coronary flow reserve, a stress SPECT scan is needed. A series of resting and stress scans could take a relatively long time. For optimal comfort, the patient would step off the scanner bed during the interval between the two scans, or the two scans would be carried out on different days. In such cases, additional CT-AC scans would be needed for accurate attenuation correction. The respiration amplitude observed by the monitoring system was 8.50 ± 5.58 (2.51 to 17.50) mm. The accuracy of the system, 0.35-mm RMS, was considered sufficient to discriminate the three respiratory phases during a single session, that is, while a subject lay continuously on the scanner bed. However, it would be difficult, using the monitoring system, to ensure inter-subject reproducibility of the amplitude of respiratory motion as well as intra-subject results obtained during different sessions. The respiratory motion was estimated by measuring positions of the infrared-reflective target placed on the abdominal surface. The amplitudes and directions of surface movements depend on the individual subject, the location of the target, and any non-linear deformation of the abdominal surface and internal organs.The registration of an attenuation map and a pre-reconstructed SPECT image, prior to reconstruction of a quantitative SPECT image corrected for attenuation and scatter, was limited to translations in three spatial directions. If a rigid-body model including rotations or a non-linear registration was employed, an image corrected with CT-AC at the EXP phase might provide a consistent result with a TCT-based scan or CT-AC at the other respiratory phases. However, the use of INS or MID attenuation maps has an advantage over the EXP attenuation map in terms of separation between the heart and the liver surfaces, which would contribute to accurate registration of attenuation maps and pre-reconstructed SPECT images. As shown in Table , translations toward caudal directions were needed to align CT attenuation maps at any respiration phases to SPECT images. The reason could be different baseline positions of the hearts during breath-hold CT acquisitions and SPECT acquisitions with breathing freely, as previously reported by Pan et al. []. For TCT attenuation map, no alignment between the attenuation map and SPECT image was needed essentially because temporal resolutions of TCT and SPECT scans for respiratory motions were nearly identical. The slight shifts of TCT attenuation maps to SPECT images in cephalad/caudal directions, 2.4 ± 2.1 mm, might be caused by global and/or intra-torso motions of subjects.
Use of breath-hold CT attenuation maps at end-inspiration and middle phases for attenuation and scatter corrections demonstrated accurate quantitative images in cardiac SPECT/CT studies. This technique might be applicable to routine clinical study. Quantitative assessment of absolute MBF and coronary flow reserve in clinical settings would be an additional potential application.
This study was supported by a Grant for Translational Research from the Ministry of Health, Labour and Welfare of Japan, a Grant for Advanced Medical Technology from the Ministry of Health, Labour and Welfare of Japan, and, in part, a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
Below are the links to the authors’ original submitted files for images.
Authors’ original file for figure 1
Authors’ original file for figure 2
Authors’ original file for figure 3
Authors’ original file for figure 4
Authors’ original file for figure 5
Authors’ original file for figure 6
The authors declare that they have no competing interests.KaK participated in the development of a respiratory motion indicator system and analysis of SPECT data. KS participated in the image processing for reconstruction of SPECT images. YH participated in the measurement of respiratory motions. TM and TZ participated in the discussion of spillover effects and misregistration effects between emission and attenuation data and helped to draft the manuscript. MF and YN carried out SPECT/CT studies as radiological technologists. KF and KeK participated as physicians. HI conceived the application of the breath-hold CT to the cardiac SPECT study and helped to draft the manuscript. All authors read and approved the final manuscript.
(1)Department of Investigative Radiology, National Cerebral and Cardiovascular Center Research Institute(2)Department of Radiology and Nuclear Medicine, National Cerebral and Cardiovascular Center Hospital(3)Graduate School of Medicine/Faculty of Medicine, Osaka University
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