diff options
| -rw-r--r-- | lib/postrunner/ActivitySummary.rb | 6 | ||||
| -rw-r--r-- | lib/postrunner/HRV_Analyzer.rb | 105 |
2 files changed, 111 insertions, 0 deletions
diff --git a/lib/postrunner/ActivitySummary.rb b/lib/postrunner/ActivitySummary.rb index c9234ac..b01dfed 100644 --- a/lib/postrunner/ActivitySummary.rb +++ b/lib/postrunner/ActivitySummary.rb @@ -14,6 +14,7 @@ require 'fit4ruby' require 'postrunner/FlexiTable' require 'postrunner/ViewFrame' +require 'postrunner/HRV_Analyzer' module PostRunner @@ -112,6 +113,11 @@ module PostRunner vo2max = @fit_activity.vo2max t.row([ 'VO2max:', vo2max ? vo2max : '-' ]) + hrv = HRV_Analyzer.new(@fit_activity) + if hrv.has_hrv_data? + t.row([ 'HRV Score:', hrv.lnrmssdx20 ]) + end + t end diff --git a/lib/postrunner/HRV_Analyzer.rb b/lib/postrunner/HRV_Analyzer.rb new file mode 100644 index 0000000..60d6134 --- /dev/null +++ b/lib/postrunner/HRV_Analyzer.rb @@ -0,0 +1,105 @@ +#!/usr/bin/env ruby -w +# encoding: UTF-8 +# +# = HRV_Analyzer.rb -- PostRunner - Manage the data from your Garmin sport devices. +# +# Copyright (c) 2015 by Chris Schlaeger <cs@taskjuggler.org> +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of version 2 of the GNU General Public License as +# published by the Free Software Foundation. +# + +module PostRunner + + # This class analyzes the heart rate variablity based on the R-R intervals + # in the given FIT file. It can compute RMSSD and a HRV score if the data + # quality is good enough. + class HRV_Analyzer + + def initialize(fit_file) + @fit_file = fit_file + collect_rr_intervals + end + + # The method can be used to check if we have valid HRV data. The FIT file + # must have HRV data, it must have correctly measured 90% of the beats and + # the measurement duration must be at least 30 seconds. + def has_hrv_data? + !@fit_file.hrv.empty? && + @missed_beats < (0.1 * @rr_intervals.length) && + total_duration > 30.0 + end + + # Return the total duration of all measured intervals in seconds. + def total_duration + @rr_intervals.inject(:+) + end + + # root mean square of successive differences + def rmssd + last_i = nil + sum = 0.0 + @rr_intervals.each do |i| + if last_i + sum += (last_i - i) ** 2.0 + end + last_i = i + end + Math.sqrt(sum / (@rr_intervals.length - 1)) + end + + # The RMSSD value is not very easy to memorize. Alternatively, we can + # multiply the natural logarithm of RMSSD by -20. This usually results in + # values between 40 (for untrained) and 100 (for higly trained) athletes. + def lnrmssdx20 + (-20.0 * Math.log(rmssd)).round.to_i + end + + private + + def collect_rr_intervals + raw_rr_intervals = [] + @fit_file.hrv.each do |hrv| + raw_rr_intervals += hrv.time.compact + end + + prev_dts = [] + avg_dt = nil + @missed_beats = 0 + @rr_intervals = [] + raw_rr_intervals.each do |dt| + # Sometimes the hrv data is missing one or more beats. The next + # detected beat is then listed with a time interval since the last + # detected beat. We try to detect these skipped beats by looking for + # time intervals that are 1.8 or more times larger than the average of + # the last 5 good intervals. + if avg_dt && dt > 1.8 * avg_dt + # If we have found skipped beats we calcluate how many beats were + # skipped. + skip = (dt / avg_dt).round.to_i + # We count the total number of skipped beats. We don't use the HRV + # data if too many beats were skipped. + @missed_beats += skip + # Insert skip times the average skipped beat intervals. + skip.times do + new_dt = dt / skip + @rr_intervals << new_dt + prev_dts << new_dt + prev_dts.shift if prev_dts.length > 5 + end + else + @rr_intervals << dt + # We keep a list of the previous 5 good intervals and compute the + # average value of them. + prev_dts << dt + prev_dts.shift if prev_dts.length > 5 + end + avg_dt = prev_dts.inject(:+) / prev_dts.length + end + end + + end + +end + |