diff --git a/rowers/forms.py b/rowers/forms.py
index eff14e8a..ab8c261f 100644
--- a/rowers/forms.py
+++ b/rowers/forms.py
@@ -703,6 +703,59 @@ class FitnessMetricForm(forms.Form):
     class Meta:
         fields = ['startdate','enddate','mode']
 
+class FitnessFitForm(forms.Form):
+    startdate = forms.DateField(
+        initial=timezone.now()-datetime.timedelta(days=365),
+        #                               widget=SelectDateWidget(years=range(1990,2050)),
+        widget=AdminDateWidget(),
+        label='Start Date')
+    enddate = forms.DateField(
+        initial=timezone.now(),
+        widget=AdminDateWidget(),
+        label='End Date')
+
+    modechoices = (
+        ('rower','indoor rower'),
+        ('water','on the water')
+        )
+
+    metricchoices = (
+        ('trimp','TRIMP'),
+        ('rscore','rScore')
+    )
+
+    fitnesstest = forms.IntegerField(required=True,initial=20,
+                                     label='Test Duration (minutes)')
+
+    kfitness = forms.IntegerField(initial=42,required=True,
+                            label='Fitness Time Constant (days)')
+
+    kfatigue = forms.IntegerField(initial=7,required=True,
+                            label='Fatigue Time Constant (days)')
+
+    metricchoice = forms.ChoiceField(required=True,
+                                      choices=metricchoices,
+                                      initial='rscore',
+                                      label='Workload Metric')
+
+    # temporary
+    k1 = forms.FloatField(required=True,initial=1.0,
+                          label='k1')
+    k2 = forms.FloatField(required=True,initial=1.0,
+                          label='k2')
+    p0 = forms.IntegerField(required=True,initial=100,label='Unfit Performance')
+
+    mode = forms.ChoiceField(required=True,
+                             choices=modechoices,
+                             initial='rower',
+                             label='Workout Mode'
+                             )
+
+    class Meta:
+        fields = ['startdate','enddate','mode','fitnesstest',
+                  'kfitness','kfatigue','metricchoice',
+                  'k1','k2','p0']
+
 class SessionDateShiftForm(forms.Form):
     shiftstartdate = forms.DateField(
         initial=timezone.now(),
diff --git a/rowers/interactiveplots.py b/rowers/interactiveplots.py
index 5923345d..6e614247 100644
--- a/rowers/interactiveplots.py
+++ b/rowers/interactiveplots.py
@@ -1528,28 +1528,35 @@ def interactive_forcecurve(theworkouts,workstrokesonly=True,plottype='scatter'):
     return [script,div,js_resources,css_resources]
 
 def fitnessfit_chart(workouts,user,workoutmode='water',startdate=None,
-                     enddate=None,nrdays=42):
+                     enddate=None,kfitness=42,kfatigue=7,fitnesstest=20,
+                     metricchoice='rscore',
+                     k1=1,k2=1,p0=100):
 
     TOOLS = 'save,pan,box_zoom,wheel_zoom,reset,tap,hover,crosshair'
 
     dates = []
-    fourminpower = []
-    hourpower = []
+    testpower = []
+    fatigues = []
+    fitnesses = []
 
     workouts = workouts.order_by('date')
     data = []
 
+    fitnesstestsecs = fitnesstest*60
+
+    # create CP data
     for w in workouts:
         cpfile = 'media/cpdata_{id}.parquet.gz'.format(id=w.id)
         try:
             df = pd.read_parquet(cpfile)
             df['workout'] = w.id
+            df['workoutdate'] = w.date.strftime('%d-%m-%Y')
             data.append(df)
         except:
             pass
 
     if len(data) == 0:
-        return pd.Series(),pd.Series(),0,pd.Series()
+        return '','Insufficient data'
     if len(data)>1:
         df = pd.concat(data,axis=0)
 
@@ -1557,7 +1564,8 @@ def fitnessfit_chart(workouts,user,workoutmode='water',startdate=None,
     errfunc = lambda pars,x,y: fitfunc(pars,x)-y
 
     for w in workouts:
-        ids = [w.id for w in workouts.filter(date__gte=w.date-datetime.timedelta(days=nrdays),
+        # Create CP data point for date range
+        ids = [w.id for w in workouts.filter(date__gte=w.date-datetime.timedelta(days=kfitness),
                                              date__lte=w.date)]
 
         powerdf = df[df['workout'].isin(ids)]
@@ -1577,48 +1585,61 @@ def fitnessfit_chart(workouts,user,workoutmode='water',startdate=None,
             thesecs = powerdf['delta'].values
             theavpower = powerdf['cp'].values
 
-            if thesecs.min() < 240 and thesecs.max() > 240:
-                ww = griddata(thesecs,theavpower,np.arange(239,241,1),method='linear',rescale=True)
-                powerfourmin = ww[1]
+            if thesecs.min() < fitnesstestsecs and thesecs.max() > fitnesstestsecs:
+                ww = griddata(thesecs,theavpower,np.array([fitnesstestsecs]),method='linear',rescale=True)
+                powertest = ww[0]
             else:
-                powerfourmin = np.nan
+                powertest = np.nan
+
 
-            if thesecs.min() < 3600 and thesecs.max() > 3600:
-                ww = griddata(thesecs,theavpower,np.arange(3599,3601,1),method='linear',rescale=True)
-                powerhour = ww[1]
-            else:
-                powerhour = np.nan
 
             dates.append(datetime.datetime.combine(w.date,datetime.datetime.min.time()))
-            fourminpower.append(powerfourmin)
-            hourpower.append(powerhour)
+            testpower.append(powertest)
+
+            # create Fitness and Fatigue number
+            fatigue = 0
+            fitness = 0
+            previousworkouts = workouts.filter(date__lte=w.date)
+            for ww in previousworkouts:
+                delta = (w.date-ww.date).days
+                weight = getattr(ww,metricchoice)
+                fatigue += weight*math.exp(-delta/kfatigue)
+                fitness += weight*math.exp(-delta/kfitness)
+
+            fatigues.append(fatigue)
+            fitnesses.append(fitness)
+
+
 
     df = pd.DataFrame({
         'date':dates,
-        'fourminpower':fourminpower,
-        'hourpower':hourpower,
+        'testpower':testpower,
+        'fatigue':fatigues,
+        'fitness':fitnesses,
     })
 
+    df['fatigue'] = k2*df['fatigue']
+    df['fitness'] = p0+k1*df['fitness']
+    df['form'] = df['fitness']-df['fatigue']
+
 
     df.sort_values(['date'],inplace=True)
 
-    df['hourdup'] = df['hourpower'].shift(1)
-    df['fourmindup'] = df['fourminpower'].shift(1)
-    df['hourpower'] = df.apply(lambda x: np.nan if abs(x['hourpower'] - x['hourdup']) < 4 \
-                               else x['hourpower'],axis=1)
-
-    df['fourminpower'] = df.apply(lambda x: np.nan if abs(x['fourminpower'] - x['fourmindup']) < 4 \
-                               else x['fourminpower'],axis=1)
 
+    df['testdup'] = df['testpower'].shift(1)
+    df['testpower'] = df.apply(lambda x: np.nan if abs(x['testpower'] - x['testdup']) < 4 \
+                               else x['testpower'],axis=1)
 
 
 
     source = ColumnDataSource(
         data = dict(
-            fourminpower = df['fourminpower'],
-            hourpower = df['hourpower'],
+            testpower = df['testpower'],
             date = df['date'],
-            fdate = df['date'].map(lambda x: x.strftime('%d-%m-%Y'))
+            fdate = df['date'].map(lambda x: x.strftime('%d-%m-%Y')),
+            fitness = df['fitness'],
+            fatigue = df['fatigue'],
+            form = df['form'],
         )
     )
 
@@ -1656,14 +1677,21 @@ def fitnessfit_chart(workouts,user,workoutmode='water',startdate=None,
                    y_range_name = "watermark",
                    )
 
-    plot.circle('date','fourminpower',source=source,fill_color='green',size=10,legend_label='4 min power')
-    plot.circle('date','hourpower',source=source,fill_color='blue',size=10,legend_label='60 min power')
-
+    plot.circle('date','testpower',source=source,fill_color='green',size=10,
+                legend_label='{fitnesstest} min power'.format(fitnesstest=fitnesstest))
 
+    plot.line('date','fitness',source=source,color='yellow',
+              legend_label='fitness')
+    plot.line('date','fatigue',source=source,color='red',
+              legend_label='fatigue')
+    plot.line('date','form',source=source,color='green',
+              legend_label='form')
 
     plot.xaxis.axis_label = 'Date'
     plot.yaxis.axis_label = 'Power (W)'
 
+    plot.legend.location = "top_left"
+
     plot.xaxis.formatter = DatetimeTickFormatter(
         days=["%d %B %Y"],
         months=["%d %B %Y"],
@@ -1673,7 +1701,7 @@ def fitnessfit_chart(workouts,user,workoutmode='water',startdate=None,
     plot.xaxis.major_label_orientation = pi/4
     plot.sizing_mode = 'stretch_both'
 
-    plot.y_range = Range1d(0,1.5*max(fourminpower))
+    plot.y_range = Range1d(0,1.5*max(testpower))
     startdate = datetime.datetime.combine(startdate,datetime.datetime.min.time())
     enddate = datetime.datetime.combine(enddate,datetime.datetime.min.time())
 
@@ -1685,8 +1713,7 @@ def fitnessfit_chart(workouts,user,workoutmode='water',startdate=None,
     hover = plot.select(dict(type=HoverTool))
 
     hover.tooltips = OrderedDict([
-        ('Power 4 minutes','@fourminpower'),
-        ('Power 1 hour','@hourpower'),
+        ('Power {fitnesstest} minutes'.format(fitnesstest=fitnesstest),'@testpower'),
         ('Date','@fdate')
     ])
 
diff --git a/rowers/templates/fitnessfit.html b/rowers/templates/fitnessfit.html
index 84c1cb5f..8c15d925 100644
--- a/rowers/templates/fitnessfit.html
+++ b/rowers/templates/fitnessfit.html
@@ -72,11 +72,22 @@
 </script>
 
 {% if rower.user %}
-<h1>Power Progress for {{ rower.user.first_name }} </h1>
+<h1>Fitness Progress for {{ rower.user.first_name }} </h1>
 {% else %}
-<h1>Power Progress for {{ user.first_name }} </h1>
+<h1>Fitness Progress for {{ user.first_name }} </h1>
 {% endif %}
 
+<p>
+  This is an experimental page. Using the form below you can set
+  a date range to compare a prediction of your form (from TRIMP or rScore values
+  representing your workload). The Fitness Time Constant is the
+  time constant describing your fitness decline when you stop training. The
+  Fatigue Time Constant (shorter than fitness time constant) is the time
+  constant describing fatigue decline after a session. You have to select
+  a test duration that represents your fitness goal and is a duration for which
+  you regularly do maximal or submaximal efforts during your regular rowing workouts.
+</p>
+
 
 <ul class="main-content">
   <li class="grid_2">
diff --git a/rowers/views/analysisviews.py b/rowers/views/analysisviews.py
index c976449b..6537fdc9 100644
--- a/rowers/views/analysisviews.py
+++ b/rowers/views/analysisviews.py
@@ -1551,17 +1551,33 @@ def fitness_from_cp_view(request,userid=0,mode='rower',
 
     therower = getrequestrower(request,userid=userid)
     theuser = therower.user
-    
 
+    kfitness = 42
+    kfatigue = 7
+    fitnesstest = 20
+    metricchoice = 'rscore'
+
+    # temp fit parameters
+    k1 = 1
+    k2 = 1
+    p0 = 100.
 
     if request.method == 'POST':
-        form = FitnessMetricForm(request.POST)
+        form = FitnessFitForm(request.POST)
         if form.is_valid():
             startdate = form.cleaned_data['startdate']
             enddate = form.cleaned_data['enddate']
             mode = form.cleaned_data['mode']
+            kfitness = form.cleaned_data['kfitness']
+            kfatigue = form.cleaned_data['kfatigue']
+            fitnesstest = form.cleaned_data['fitnesstest']
+            metricchoice = form.cleaned_data['metricchoice']
+            # temporary manual "fit" parameters
+            k1 = form.cleaned_data['k1']
+            k2 = form.cleaned_data['k2']
+            p0 = form.cleaned_data['p0']
     else:
-        form = FitnessMetricForm()
+        form = FitnessFitForm()
 
     workouts = Workout.objects.filter(user=therower,date__gte=startdate,
                                       date__lte=enddate,
@@ -1576,6 +1592,11 @@ def fitness_from_cp_view(request,userid=0,mode='rower',
         workouts,theuser,
         workoutmode=mode,startdate=startdate,
         enddate=enddate,
+        kfitness=kfitness,
+        kfatigue=kfatigue,
+        fitnesstest=fitnesstest,
+        metricchoice=metricchoice,
+        k1=k1,k2=k2,p0=p0
     )
 
     breadcrumbs = [
diff --git a/rowers/views/statements.py b/rowers/views/statements.py
index fc2cdb13..19f6fa1b 100644
--- a/rowers/views/statements.py
+++ b/rowers/views/statements.py
@@ -76,7 +76,7 @@ from rowers.forms import (
     disqualifiers,SearchForm,BillingForm,PlanSelectForm,
     VideoAnalysisCreateForm,WorkoutSingleSelectForm,
     VideoAnalysisMetricsForm,SurveyForm,HistorySelectForm,
-    StravaChartForm,
+    StravaChartForm,FitnessFitForm
     )
 
 from django.urls import reverse, reverse_lazy